Magnetic phase isolating harmonic filter for multi-phase power apparatus and method of use thereof

ABSTRACT

The invention comprises a harmonic filter apparatus and method of use thereof for magnetically isolating and filtering individual phases of three-phase power comprising a delta circuit that includes: (1) a first leg connecting to a second leg and a third leg and (2) first circuitry on the first leg matching second circuitry on the second leg, the first circuitry comprising at least two contactors electrically wired in parallel, the harmonic filter magnetically isolating individual phases of three-phase power, where inductor—coupled inductor pairs couple apexes of the delta circuit to individual phases of the three-phase power.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 16/727,861, filed Dec. 26, 2019, which is acontinuation-in-part of U.S. patent application Ser. No. 16/540,025filed Aug. 13, 2019, which is a continuation of U.S. patent applicationSer. No. 15/635,113 filed Jun. 27, 2017, which is a continuation-in-partof U.S. patent application Ser. No. 14/987,675 filed Jan. 4, 2016, whichis:

-   -   a continuation-in-part of U.S. patent application Ser. No.        14/260,014 filed Apr. 23, 2015; and    -   a continuation-in-part of U.S. patent application Ser. No.        13/954,887 filed Jul. 30, 2013, which is a continuation-in-part        of U.S. patent application Ser. No. 13/470,281 filed May 12,        2012, which is a continuation-in-part of U.S. patent application        Ser. No. 13/107,828 filed May 13, 2011, which is a        continuation-in-part of U.S. patent application Ser. No.        12/098,880 filed Apr. 4, 2008, which claims benefit of U.S.        provisional patent application No. 60/910,333 filed Apr. 5,        2007, all of which are incorporated herein in their entirety by        this reference thereto.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to a magnetic phase isolating harmonic filter forprocessing multi-phase power.

Discussion of the Prior Art

Power is generated from a number of sources. The generated power isnecessarily converted, such as before entering the power grid or priorto use. In many industrial applications, electromagnetic components,such as inductors and capacitors, are used in power filtering. Importantfactors in the design of power filtering methods and apparatus includecost, size, signal, noise, efficiency, resonant points, inductorimpedance, inductance at desired frequencies, and/or inductancecapacity.

For example, when a metal-oxide-semiconductor field-effect transistor(MOSFET) or an insulated gate bipolar transistor (IGBT) switches at highfrequencies, output from the inverter going to a motor now hassubstantial frequencies in the 50-100 kHz range. The power cablesexiting the drive or inverter going to a system load using standardindustrial power cables were designed for 60 Hz current. Whenfrequencies in the 50-100 kHz range are added to the current spectrum,the industrial power cables overheat because of the high frequencytravels only on the outside diameter of the conductor causing a severeincrease in AC resistance of the cable and resultant overheating of thecables and any associated device, such as a motor.

What is needed is a more efficient electrical filter apparatus andmethod of use thereof.

SUMMARY OF THE INVENTION

The invention comprises a magnetic phase isolating harmonic filterapparatus and method of use thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention is derived byreferring to the detailed description and described embodiments whenconsidered in connection with the following illustrative figures. In thefollowing figures, like reference numbers refer to similar elements andsteps throughout the figures.

FIG. 1A illustrates a power filtering process, FIG. 1B illustrates a lowfrequency power system, FIG. 1C illustrates a high frequency powerprocessing system, FIG. 1D illustrates a grid power filtering process,FIG. 1E illustrates an AC power processing system, FIG. 1F illustratesan enclosed AC power processing system, FIG. 1G illustrates a generatedpower processing system, and FIG. 1H illustrates a high frequency powerprocessing system;

FIG. 2 illustrates multi-phase inductor/capacitor component mounting anda filter circuit for power processing;

FIG. 3 further illustrates capacitor mounting;

FIG. 4 illustrates a face view of an inductor;

FIG. 5 illustrates a side view of an inductor;

FIG. 6A illustrates an inductor core and an inductor winding and FIG. 6Billustrated inductor core particles;

FIG. 7 provides exemplary BH curve results;

FIG. 8 illustrates a sectioned inductor;

FIG. 9 illustrates partial circumferential inductor winding spacers;

FIG. 10 illustrates an inductor with multiple winding spacers;

FIG. 11 illustrates two winding turns on an inductor;

FIG. 12 illustrates multiple wires winding an inductor;

FIG. 13 illustrates tilted winding spacers on an inductor;

FIG. 14 illustrates tilted and rotated winding spacers on an inductor;

FIG. 15 illustrates a capacitor array;

FIG. 16 illustrates a Bundt pan inductor cooling system;

FIG. 17A illustrates formation of a heat transfer enhanced pottingmaterial;

FIG. 17B illustrates an epoxy-sand potting material, and FIG. 17Cillustrates the potting material about an electrical component;

FIG. 18 illustrates a potted cooling line inductor cooling system;

FIG. 19 illustrates a wrapped inductor cooling system;

FIG. 20 illustrates an oil/coolant immersed cooling system;

FIG. 21 illustrates use of a chill plate in cooling an inductor;

FIG. 22 illustrates a refrigerant phase change on the surface of aninductor;

FIG. 23 illustrates multiple turns, each turn wound in parallel;

FIG. 24A and FIG. 24C illustrate powdered non-annular, 2-phase inductorsand FIG. 24B illustrates a powdered non-annular, 3-phase inductor;

FIG. 25 illustrates filter attenuation for iron and powdered cores;

FIG. 26 illustrates a high frequency inductor-capacitor filter;

FIG. 27A illustrates an inductor-capacitor filter and FIG. 27Billustrates corresponding filter attenuation profiles as a function offrequency;

FIG. 28A illustrates a high roll-off low pass filter and FIG. 28Billustrates corresponding filter attenuation profiles as a function offrequency;

FIG. 29A illustrates a flat winding wire; FIG. 29B, FIG. 29C and FIG.29D compare perimeter lengths of winding wires having differing geometrywith a common cross-section area;

FIG. 30A illustrates a flat winding wound around an inductor core, FIG.30B illustrates air flow between winding turns, and FIG. 30C illustrateslayers of windings;

FIG. 31 illustrates a process of balancing magnetic fields in processing3-phase power line transmissions;

FIG. 32A, FIG. 32C, and FIG. 32D illustrate an equal coupling commonmode electrical system for processing a 3-phase power line transmissionillustrated in FIG. 32B;

FIG. 33 illustrates a first unequal coupling common mode electricalsystem for processing a 3-phase power line transmission;

FIG. 34 illustrates a second unequal coupling common mode electricalsystem for processing a 3-phase power line transmission;

FIG. 35 illustrates a four post inductor system;

FIG. 36A, FIG. 36B, and FIG. 36C respectively illustrate one, two, andthree turns about a toroidal inductor core;

FIG. 37A, FIG. 37B, and FIG. 37C respectively illustrate one, two, andthree flat turns about a toroidal inductor core;

FIG. 38 illustrates a cabinet housing a power processing system;

FIG. 39A illustrates a bent flat turn about an inductor core and FIG.39B and FIG. 39C illustrate one and two flat turns about a toroidalcore, respectively;

FIG. 40 illustrates an arced helical coil;

FIG. 41 illustrates a method of manufacturing an inductor;

FIG. 42 illustrates a method of assembly of an inductor;

FIG. 43A illustrates a sectioned toroid inductor core and FIG. 43B andFIG. 43C respectively illustrate a close fit and snap-together interfaceof toroid inductor core sections;

FIG. 44A and FIG. 44B illustrate cast protrusions of a winding havinggaps and gaps filled with cooling lines, respectively;

FIG. 45A and FIG. 45B illustrate cooling lines in gaps in a planar andperspective view, respectively;

FIG. 46 illustrates a clamshell cooling system;

FIG. 47A and FIG. 47B illustrate volumes and thicknesses of a castwinding, FIG. 47C illustrates aperture filling capacity of castwindings, and FIG. 47D and FIG. 47E illustrate heat sinks as elements ofa winding;

FIG. 48 illustrates use of a harmonic filter;

FIG. 49 illustrates a contactor controller;

FIG. 50 illustrates a harmonic filter;

FIG. 51A and FIG. 51B illustrate stacked inductors and FIG. 51C, FIG.51D, and FIG. 51E illustrate air cooling stacked inductors;

FIG. 52A and FIG. 52B illustrates strapped inductors from a side-viewand a perspective view, respectively;

FIG. 53 illustrates a motor linked to a load;

FIG. 54 illustrates a delta-circuit with auxiliary connectors;

FIG. 55 illustrates a delta-circuit with in-leg connectors;

FIG. 56 illustrates a delta-circuit with parallel connectors;

FIG. 57 illustrates parallel inductors;

FIG. 58 illustrates a capacitor in parallel with parallel inductors;

FIG. 59A and FIG. 59B illustrates a metallized film and a metallizedfilm capacitor, respectively;

FIG. 60A illustrates a circular inductor core, FIG. 60B illustrates anoval inductor core, FIG. 60C illustrates a square inductor core, andFIG. 60D illustrates a rectangular inductor core;

FIG. 61 illustrates mechanically joined/fabricated windings;

FIG. 62A illustrates a first winding sub-element/connector, FIG. 62B andFIG. 62C illustrate a second winding sub-element/wrap, and FIG. 62Dillustrates a winding terminal connector;

FIG. 63A illustrates a multi-inductor tube and FIG. 63B and FIG. 63Cillustrate multiple inductors in the multi-inductor tube; and FIG. 64Aillustrates a hip cabinet on a drive cabinet and FIG. 64B illustratesaccessible inductor filter connectors in the hip cabinet.

Elements and steps in the figures are illustrated for simplicity andclarity and have not necessarily been rendered according to anyparticular sequence. For example, steps that are performed concurrentlyor in different order are illustrated in the figures to help improveunderstanding of embodiments of the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The invention comprises a harmonic filter apparatus and method of usethereof for magnetically isolating and filtering individual phases ofthree-phase power comprising a delta circuit that includes: (1) a firstleg connecting to a second leg and a third leg and (2) first circuitryon the first leg matching second circuitry on the second leg, the firstcircuitry comprising at least two contactors electrically wired inparallel, the harmonic filter magnetically isolating individual phasesof three-phase power, where inductor—coupled inductor pairs coupleapexes of the delta circuit to individual phases of the three-phasepower.

The inductor is optionally used to filter/invert/convert power. Theinductor optionally comprises a distributed gap core and/or a powderedcore material. In one example, the minimum carrier frequency is abovethat usable by an iron-steel inductor, such as greater than tenkiloHertz at fifty or more amperes. Optionally, the inductor is used inan inverter/converter apparatus, where output power has a carrierfrequency, modulated by a fundamental frequency, and a set of harmonicfrequencies, in conjunction with a notched low-pass filter, a low passfilter combined with a notch filter and a high frequency roll offfilter, and/or one or more of a silicon carbide, gallium arsenide,and/or gallium nitride based transistor.

In another example, the inductor is an element of an inductor-capacitorfilter, where the filter comprises: an inductor with a distributed gapcore and/or a powdered core in a notch filter circuit, such as a notchedlow-pass filter or a low pass filter combined with a notch filter and ahigh frequency roll off filter. The resulting distributed gap inductorbased notch filter efficiently passes a carrier frequency of greaterthan 700, 800, or 1000 Hz while still sufficiently attenuating afundamental frequency at 1500, 2000, or 2500 Hz, which is not achievablewith a traditional steel based inductor due to the physical propertiesof the steel at high currents and voltages, such as at fifty or moreamperes.

In another example, the inductor is used to filter/convert power, wherethe inductor comprises a distributed gap core and/or a powdered core.The inductor core is wound with one or more turns, where multiple turnsare optionally electrically wired in parallel. In one example, a minimumcarrier frequency is above that usable by traditional inductors, such asa laminated steel inductor, an iron-steel inductor, and/or a siliconsteel inductor, for at least fifty amperes at at least one kHz, as thecarrier frequency is the resonant point of the inductor and harmonicsare thus not filtered using the iron-steel inductor core. In starkcontrast, the distributed gap core allows harmonic removal/attenuationat greater than ten kiloHertz at fifty or more amperes. The core isoptionally an annular core, a toroid core, a rod-shaped core, a straightcore, a single core, or a core used for multiple phases, such as a ‘C’or ‘E’ core. Herein, an annular core optionally refers to a doughnutshaped core. Optionally, the inductor is used in an inductor/converterapparatus, where output power has a carrier frequency, modulated by afundamental frequency, and a set of harmonic frequencies, in conjunctionwith one or more of a silicon carbide, gallium arsenide, and/or galliumnitride based transistor, such as a metal-oxide-semiconductorfield-effect transistor (MOSFET).

In yet another embodiment, an inverter and/or an inverter convertersystem yielding high frequency harmonics, referred to herein as a highfrequency inverter, is coupled with a high frequency filter to yieldclean power, reduced high frequency harmonics, and/or an enhanced energyprocessing efficiency system. In one case, a silicon carbidemetal-oxide-semiconductor field-effect transistor (MOSFET) is used inthe conversion of power from the grid and the MOSFET outputs current,voltage, energy, and/or high frequency harmonics greater than 60 Hz toan output filter, such as a distributed gap inductor, which filters theoutput of the MOSFET. In one illustrative example, a high frequencyinductor and/or converter apparatus is coupled with a high frequencyfilter system, such as an inductor linked to a capacitor, to yieldnon-sixty Hertz output. In another illustrative example, aninductor/converter apparatus using a silicon carbide transistor outputspower having a carrier frequency, modulated by a fundamental frequency,and a set of harmonic frequencies. A filter, comprising the pottedinductor having a distributed gap core material and optional magnetwires, receives power output from the inverter/converter and processesthe power by passing the fundamental frequency while reducing amplitudeof the harmonic frequencies.

In another embodiment, a high frequency inverter/high frequency filtersystem is used in combination with a distributed gap inductor,optionally for use with medium voltage power, apparatus and method ofuse thereof, is provided for processing harmonics from greater than 60,65, 100, 1950, 2000, 4950, 5000, 6950, 7000, 10,000, 50,000, and/or100,000 Hertz.

In another embodiment, an inductor-capacitor filter comprises: aninductor with a distributed gap core and/or a powdered core in a notchfilter circuit, such as a notched low-pass filter or a low pass filtercombined with a notch filter and a high frequency roll off filter. Theresulting distributed gap inductor based notch filter efficiently passesa carrier frequency of greater than 700, 800, or 1000 Hz while stillsufficiently attenuating a fundamental frequency at 1500, 2000, or 2500Hz, which is not achievable with a traditional steel based inductor dueto the physical properties of the steel at high currents and voltages,such as at fifty or more amperes.

In yet still another embodiment, a high frequency inverter/highfrequency filter system is used in combination with an inductor mountingand cooling system.

In still yet another embodiment, a high frequency inverter/highfrequency filter system is used in combination with a distributed gapmaterial used in an inductor couple with an inverter and/or converter.

Methods and apparatus according to various embodiments preferablyoperate in conjunction with an inductor and/or a capacitor. For example,an inverter/converter system using at least one inductor and at leastone capacitor optionally mounts the electromagnetic components in avertical format, which reduces space and/or material requirements. Inanother example, the inductor comprises a substantially toroidal orannular core and a winding. The inductor is preferably configured forhigh current applications, such as at or above about 50, 100, or 200amperes; for medium voltage power systems, such as power systemsoperating at about 2,000 to 5,000 volts; and/or to filter highfrequencies, such as greater than about 60, 100, 1000, 2000, 3000, 4000,5000, or 9000 Hz. In yet another example, a capacitor array ispreferably used in processing a provided power supply. Optionally, thehigh frequency filter is used to selectively pass higher frequencyharmonics.

Embodiments are described partly in terms of functional components andvarious assembly and/or operating steps. Such functional components areoptionally realized by any number of components configured to performthe specified functions and to achieve the various results. For example,embodiments optionally use various elements, materials, coils, cores,filters, supplies, loads, passive components, and/or active components,which optionally carry out functions related to those described. Inaddition, embodiments described herein are optionally practiced inconjunction with any number of applications, environments, and/orpassive circuit elements. The systems and components described hereinmerely exemplify applications. Further, embodiments described herein,for clarity and without loss of generality, optionally use any number ofconventional techniques for manufacturing, assembling, connecting,and/or operation. Components, systems, and apparatus described hereinare optionally used in any combination and/or permutation.

Electrical System

An electrical system preferably includes an electromagnetic componentoperating in conjunction with an electric current to create a magneticfield, such as with a transformer, an inductor, and/or a capacitorarray.

Referring now to FIG. 1A, in one embodiment, the electrical systemcomprises an inverter/converter system configured to output: (1) acarrier frequency, the carrier frequency modulated by a fundamentalfrequency, and (2) a set of harmonic frequencies of the fundamentalfrequency. The inverter/converter 130 system optionally includes avoltage control switch 131, such as a silicon carbide insulated gatebipolar transistor 133. Optionally power output by theinverter/converter system is processed using a downstream-circuitelectrical power filter, such as an inductor and a capacitor, configuredto: substantially remove the carrier frequency, pass the fundamentalfrequency, and reduce amplitude of a largest amplitude harmonicfrequency of the set of harmonic frequencies by at least ninety percent.A carrier frequency is optionally any of: a nominal frequency or centerfrequency of an analog frequency modulation, phase modulation, ordouble-sideband suppressed-carrier transmission, AM-suppressed carrier,or radio wave. For example a carrier frequency is an unmodulatedelectromagnetic wave or a frequency-modulated signal.

In another embodiment, the electrical system comprises aninverter/converter system having a filter circuit, such as a low-passfilter and/or a high-pass filter. The power supply or inverter/convertercomprises any suitable power supply or inverter/converter, such as aninverter for a variable speed drive, an adjustable speed drive, and/oran inverter/converter that provides power from an energy device.Examples of an energy device include an electrical transmission line, athree-phase high power transmission line, a generator, a turbine, abattery, a flywheel, a fuel cell, a solar cell, a wind turbine, use of abiomass, and/or any high frequency inverter or converter system. Theterm three-phase power is often used to describe a common method ofalternating current power generation, transmission, and distribution andis a type of polyphase system most commonly used by electric gridsworldwide to transfer power.

The electrical system described herein is optionally adaptable for anysuitable application or environment, such as variable speed drivesystems, uninterruptible power supplies, backup power systems,inverters, and/or converters for renewable energy systems, hybrid energyvehicles, tractors, cranes, trucks and other machinery using fuel cells,batteries, hydrogen, wind, solar, biomass and other hybrid energysources, regeneration drive systems for motors, motor testingregenerative systems, and other inverter and/or converter applications.Backup power systems optionally include, for example, superconductingmagnets, batteries, and/or flywheel technology. Renewable energy systemsoptionally include any of: solar power, a fuel cell, a wind turbine,hydrogen, use of a biomass, and/or a natural gas turbine.

In various embodiments, the electrical system is adaptable for energystorage or a generation system using direct current (DC) or alternatingcurrent (AC) electricity configured to backup, store, and/or generatedistributed power. Various embodiments described herein are particularlysuitable for high current applications, such as currents greater thanabout one hundred amperes (A), currents greater than about two hundredamperes, and more particularly currents greater than about four hundredamperes. Embodiments described herein are also suitable for use withelectrical systems exhibiting multiple combined signals, such as one ormore pulse width modulated (PWM) higher frequency signals superimposedon a lower frequency waveform. For example, a switching element maygenerate a PWM ripple on a main supply waveform. Such electrical systemsoperating at currents greater than about one hundred amperes operatewithin a field of art substantially different than low power electricalsystems, such as those operating at low-ampere levels or at about 2, 5,10, 20, or 50 amperes.

Various embodiments are optionally adapted for high-current invertersand/or converters. An inverter produces alternating current from adirect current. A converter processes AC or DC power to provide adifferent electrical waveform. The term converter denotes a mechanismfor either processing AC power into DC power, which is a rectifier, orderiving power with an AC waveform from DC power, which is an inverter.An inverter/converter system is either an inverter system or a convertersystem. Converters are used for many applications, such as rectificationfrom AC to supply electrochemical processes with large controlled levelsof direct current, rectification of AC to DC followed by inversion to acontrolled frequency of AC to supply variable-speed AC motors,interfacing DC power sources, such as fuel cells and photoelectricdevices, to AC distribution systems, production of DC from AC power forsubway and streetcar systems, for controlled DC voltage forspeed-control of DC motors in numerous industrial applications, and/orfor transmission of DC electric power between rectifier stations andinverter stations within AC generation and transmission networks.

Filtering

Referring now to FIG. 1A, a power processing system 100 is provided. Thepower processing system 100 operates on current and/or voltage systems.FIG. 1A figuratively shows how power is moved from a grid 110 to a loadand how power is moved from a generator 154 to the grid 110 through aninverter/converter system 130. Optionally, a first filter 120 is placedin the power path between the grid 100 and the inverter/converter system130. Optionally, a second filter 140 is positioned between theinverter/converter system 130 and a load 152 or a generator 154. Thesecond filter 140 is optionally used without use of the first filter120. The first filter 120 and second filter 140 optionally use anynumber and configuration of inductors, capacitors, resistors, junctions,cables, and/or wires.

Still referring to FIG. 1A, in a first case, power or current from thegrid 110, such as an AC grid, is processed to provide current or power150, such as to a load 152. In a second case, the current or power 150is produced by a generator and is processed by one or more of the secondfilter 140, inverter/converter system 130, and/or first filter 120 fordelivery to the grid 110. In the first case, a first filter 120 is usedto protect the AC grid from energy reflected from the inverter/convertersystem 130, such as to meet or exceed IEEE 519 requirements for gridtransmission. Subsequently, the electricity is further filtered, such aswith the second filter 140 or is provided to the load 152 directly. Inthe second case, the generated power 154 is provided to theinverter/converter system 130 and is subsequently filtered, such as withthe first filter 120 before supplying the power to the AC grid. Examplesfor each of these cases are further described, infra.

Referring now to FIG. 1B, a low frequency power processing system 101 isillustrated where power from the grid 110 is processed by a lowfrequency inverter 132 and the processed power is delivered to a motor156. The low frequency power system 101 uses traditional 60 Hz/120V ACpower and the low frequency inverter 132 yields output in the 30-90 Hzrange, referred to herein as low frequency and/or standard frequency. Ifthe low frequency inverter 132 outputs high frequency power, such as 60+harmonics or higher frequency harmonics, such as about 2000, 5000, or7000 Hz, then traditional silicon iron steel in low frequency inverters132, low frequency inductors, and/or low frequency power lines overheat.These inductors overheat due to excessive core losses and AC resistancelosses in the conductors in the circuit. The overheating is a directresult of the phenomenon known as skin loss, where the high frequenciesonly travel on the outside diameter of a conductor, which causes anincrease in AC resistance of the cable, the resistance resultant insubsequent overheating.

Referring now to FIG. 1C, a high frequency power processing system 102is illustrated, where a high frequency filter 144 is inserted betweenthe inverter/converter 130 and/or a high frequency inverter 134 and theload 152, motor 156, or a permanent magnet motor 158. For clarity ofpresentation and without limitation, the high frequency filter, aspecies of the second filter 140, is illustrated between a highfrequency inverter 134 and the permanent magnet motor 158. The highfrequency inverter 134, which is an example of the inverter converter130, yields output power having frequencies or harmonics in the range of2,000 to 100,000 Hz, such as at about 2000, 5000, and 7000 Hz.

In a first example, the high frequency inverter 134 is a MOSFET inverterthat uses silicon carbide and is referred to herein as a silicon carbideMOSFET. In a second example, the high frequency filter 144 uses aninductor comprising at least one of: a distributed gap material, amagnetic material and a coating agent, Sendust, and/or any of theproperties described, infra, in the “Inductor Core/Distributed Gap”section. In a preferred embodiment, output from the high frequencyinverter 134 is processed by the high frequency filter 144 as the highfrequency output filters described herein do not overheat due to themagnetic properties of the core and/or windings of the inductor and thehigher frequency filter removes high frequency harmonics that wouldotherwise result in overheating of an electrical component. Herein, areduction in high frequency harmonics is greater than a 20, 40, 60, 80,90, and/or 95 percent reduction in at least one high frequency harmonic,such as harmonic of a fundamental frequency modulating a carrierfrequency. Preferably, the inductor/capacitor combination describedherein reduces amplitude of the largest 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ormore largest harmonic frequencies by at least 10, 20, 30, 40, 50, 60,70, 80, 90, 95, or 99 percent. In one particular case, the distributedgap material used in the inductor described herein, processes outputfrom a silicon carbide MOSFET with significantly less loss than aninductor using silicon iron steel.

Herein, for clarity of presentation, silicon carbide and/or a compoundof silicon and carbon is used to refer to any of the 250+ forms ofsilicon carbide, alpha silicon carbide, beta silicon carbide, a polytypecrystal form of silicon carbide, and/or a compound, where at least 80,85, 90, 95, 96, 97, 98, or 99 percent of the compound comprises siliconand carbon by weight, such as produced by the Lely method or as producedusing silicon oxide found in plant matter. The compound and/or additivesof silicon and carbon is optionally pure or containssubstitutions/impurities of any of nitrogen, phosphorus, aluminum,boron, gallium, and beryllium. For example, doping the silicon carbidewith boron, aluminum, or nitrogen is performed to enhance conductivity.Further, silicon carbide refers to the historically named carborundumand the rare natural mineral moissanite.

Insulated gate bipolar transistors are used in examples herein forclarity and without loss of generality. Generally, MOSFETs and insulategate bipolar transistors (IGBTs) are examples of the switching devices,which also include free-wheeling diodes (FWDs) also known asfreewheeling diodes. Further, a metal-oxide-semiconductor field-effecttransistor (MOSFET) is optionally used in place or in combination withan IGBT. Both the IGBT and MOSFET are transistors, such as foramplifying or switching electronic signals and/or as part of anelectrical filter system. While a MOSFET is used as jargon in the field,the metal in the acronym MOSFET is optionally and preferably a layer ofpolycrystalline silicon or polysilicon. Generally an IGBT or MOSFET usesa form of gallium arsenide, silicon carbide, and/or gallium nitridebased transistor.

The use of the term silicon carbide MOSFET includes use of siliconcarbide in a transistor. More generally, silicon carbide (SiC) crystals,or wafers are used in place of silicon (Si) and/or gallium arsenide(GaAs) in a switching device, such as a MOSFET, an IGBT, or a FWD. Moreparticularly, a Si PiN diode is replaced with a SiC diode and/or a SiCSchottky Barrier Diode (SBD). In one preferred case, the IGBT or MOSFETis replaced with a SiC transistor, which results in switching lossreduction, higher power density modules, and cooler runningtemperatures. Further, SiC has an order of magnitude greater breakdownfield strength compared to Si allowing use in high voltage inverters.For clarity of presentation, silicon carbide is used in examples, butgallium arsenide and/or gallium nitride based transistors are optionallyused in conjunction with or in place of the silicon carbide crystals.

Still referring to FIG. 1C, silicon carbide MOSFETs have considerablylower switching losses than conventional MOSFET technologies. Theselower losses allow the silicon carbide MOSFET module to switch atsignificantly higher switching frequencies and still maintain thenecessary low switching losses needed for the efficiency ratings of theinverter system. In a preferred embodiment, three phase AC power isprocessed by an inverter/converter and further processed by an outputfilter before delivery to a load. The output filter optionally uses anyof the inductor materials, windings, shapes, configurations, mountingsystems, and/or cooling systems described herein.

Referring now to FIG. 1D, an example of the high frequency inverter 134and a high frequency inductor-capacitor filter 145 in a singlecontaining unit 160 or housing is figuratively illustrated in a combinedpower filtering system 103. In this example, the high frequency inverter134 is illustrated as an alternating current to direct current converter135 and as a direct current to alternating current converter 136, thesecond filter 140 is illustrated as the high frequency LC filter 145,and the load 152 is illustrated as a permanent magnet motor 158.

Herein, the permanent magnet motor operates using frequencies of 90-2000Hz, such as greater than 100, 200, 500, or 1000 Hz and less than 2000,1500, 1000, or 500 Hz. The inventor has determined that use of thesingle containing unit 160 to contain an inverter 132 and high frequencyfilter 145 is beneficial when AC drives begin to use silicon carbideMOSFET's and the switching frequency on high power drives goes up, suchas to greater than 2000, 40,000, or 100,000 Hz. The inventor has furtherdetermined that when MOSFET's operate at higher frequencies an outputfilter, such as an L-C filter or the high frequency filter 144, isrequired because the cables overheat from high harmonic frequenciesgenerated using a silicon carbide MOSFET if not removed.

Still referring to FIG. 1D, the alternating current to direct currentconverter 135 and the direct current to alternating current converter136 are jointly referred to as an inverter, a variable speed drive, anadjustable speed drive, an adjustable frequency drive, and/or anadjustable frequency inverter. For clarity of presentation and withoutloss of generality, the term variable speed drive is used herein torefer to this class of drives. The inventor has determined that use of adistributed gap filter, as described supra, in combination with thevariable speed drive is used to remove higher frequency harmonics fromthe output of the variable speed drive and/or to pass selectedfrequencies, such as frequencies from 90 to 2000 Hz to a permanentmagnet motor. The inventor has further determined that the highfrequency filter 144, such as the high frequency inductor-capacitorfilter 145 is preferably coupled with the direct current to alternatingcurrent converter 136 of the inverter 132 or high frequency inverter134.

Cooling the output filter is described, infra, however, the coolingunits described, infra, preferably contain the silicon carbide MOSFET ora silicon carbide IGBT inverter so that uncooled output wires are notused between the silicon carbide inverter and the high frequency LCfilter 145 where loss and/or failure due to heating would occur. Hence,the conductors from the inverter 145 are preferably cooled, in onecontainer or multiple side-by-side containers, without leaving a cooledenvironment until processed by the high frequency filter 144 or highfrequency LC filter 145.

Still referring to FIG. 1D, where the motor or load 152 is a longdistance from an AC drive, the capacitance of the long cables amplifiesthe harmonics leaving the AC drive where the amplified harmonics hit themotor. A resulting corona on the motor windings causes magnet wire inthe motor windings to short between turns, which results in motorfailure. The high frequency filter 144 is used in these cases to removeharmonics, increase the life of the motor, enhance reliability of themotor, and/or increase the efficiency of the motor. Particularly, thesilicon carbide MOSFET/high frequency filter 144 combination finds usesin electro submersible pumps, for lifting oil deep out of the ground,and/or in fracking applications. Further, the silicon carbideMOSFET/high frequency filter 144 combination finds use generally inpermanent motor applications, which spin at much higher speeds andrequire an AC drive to operate. For example, AC motors used in largetonnage chillers and air compressors will benefit from the highfrequency LC filter 145/silicon carbide MOSFET combination.

Referring now to FIG. 1E, an example of AC power processing system 104processing AC power from the grid 110 is provided. In this case,electricity flows from the AC grid to the load 152. In this example, ACpower from the grid 110 is passed through an optional input filter 122to the inverter/converter system 130. The input filter 122 uses at leastone inductor and optionally uses at least one capacitor and/or otherelectrical components. The input filter functions to protect quality ofpower on the AC grid from harmonics or energy reflected from theinverter/converter system 130 and/or to filter power from the grid 110.Output from the inverter/converter system 130 is subsequently passedthrough an output filter 142, which is an example of a second filter 140in FIG. 1A. The output filter 142 includes at least one inductor andoptionally includes one or more additional electrical components, suchas one or more capacitors. Output from the output filter 142 issubsequently delivered to the load 152, such as to a motor, chiller, orpump. In a first instance, the load 152 is an inductor motor, such as aninductor motor operating at about 50 or 60 Hz or in the range of 30-90Hz. In a second instance, the load 152 is a permanent magnet motor, suchas a motor having a fundamental frequency range of about 90 to 2000 Hzor more preferably in the range of 250 to 1000 Hz.

Referring now to FIG. 1F, an enclosed AC power processing system 105 isillustrated. In this example, the input filter 122, inverter/converter130, and output filter 142 are enclosed in a single container 162, forcooling, weight, durability, and/or safety reasons. Optionally, thesingle container 162 is a series of 2, 3, 4 or more containers proximateeach other, such as where closest sided elements are within less than0.1, 0.5, 1, or 5 meters from each other or are joined to each other. Inthe illustrated case, the input filter 122 is an inputinductor/capacitor/inductor filter 123, the output filter 142 is anoutput inductor/capacitor filter 143, and the load 152 is a motor 152.

Referring now to FIG. 1G, an example of a generated power processingsystem 106 processing generated power from the generator 154 isprovided. In this case, electricity flows from the generator 154 to thegrid 110. The generator 154 provides power to the inverter/convertersystem 130. Optionally, the generated power is processed through agenerator filter 146 before delivery to the inverter/converter system130. Power from the inverter/converter system 130 is filtered with agrid tie filter 124, which includes at least one inductor and optionallyincludes one or more additional electrical components, such as acapacitor and/or a resistor. Output from the grid tie filter 124, whichis an example of the first filter 120 in FIG. 1A, is delivered to thegrid 110. A first example of a grid tie filter 124 is a filter using aninductor. A second example of a grid tie filter 124 is a filter using afirst inductor, a capacitor, and a second inductor for each phase ofpower. Optionally, generated output from the generator 154 afterprocessing with the inverter/converter system 130 is filtered using atleast one inductor and passed directly to a load, such as a motor,without going to the grid 110.

In the power processing system 100, the power supply system or inputpower includes any other appropriate elements or systems, such as avoltage or current source and a switching system or element. The supplyoptionally operates in conjunction with various forms of modulation,such as pulse width modulation, resonant conversion, quasi-resonantconversion, and/or phase modulation.

Filter circuits in the power processing system 100 are configured tofilter selected components from the supply signal. The selectedcomponents include any elements to be attenuated or eliminated from thesupply signal, such as noise and/or harmonic components. For example,filter circuits reduce total harmonic distortion. In one embodiment, thefilter circuits are configured to filter higher frequency harmonics overthe fundamental frequency. Examples of fundamental frequencies include:direct current (DC), 50 Hz, 60 Hz, and/or 400 Hz signals. Examples ofhigher frequency harmonics include harmonics over about 300, 500, 600,800, 1000, 2000, 5000, 7000, 10,000, 50,000 and 100,000 Hz in the supplysignal, such as harmonics induced by the operating switching frequencyof insulated gate bipolar transistors (IGBTs) and/or any otherelectrically operated switches, such as via use of a MOSFET. The filtercircuit optionally includes passive components, such as aninductor-capacitor filter comprised of an inductor, a capacitor, and insome embodiments a resistor. The values and configuration of theinductor and the capacitor are selected according to any suitablecriteria, such as to configure the filter circuits to a selected cutofffrequency, which determines the frequencies of signal componentsfiltered by the filter circuit. The inductor is preferably configured tooperate according to selected characteristics, such as in conjunctionwith high current without excessive heating or operating within safetycompliance temperature requirements.

Power Processing System

The power processing system 100 is optionally used to filter single ormulti-phase power, such as three phase power. Herein, for clarity ofpresentation AC input power from the grid 110 or input power is used inthe examples. Though not described in each example, the componentsand/or systems described herein additionally apply generator systems,such as the system for processing generated power.

Referring now to FIG. 2 , an illustrative example of multi-phase powerfiltering is provided. Input power 112 is processed using the powerprocessing system 100 to yield filtered and/or transformed output power160. In this example, three-phase power is processed with each phaseseparately filtered with an inductor-capacitor filter. The three phases,of the three-phase input power, are denoted U1, V1, and W1. The inputpower 112 is connected to a corresponding phase terminal U1 220, V1 222,and/or W1 224, where the phase terminals are connected to or integratedwith the power processing system 100. For clarity, processing of asingle phase is described, which is illustrative of multi-phase powerprocessing. The input power 112 is then processed by sequential use ofan inductor 230 and a capacitor 250. The inductor and capacitor systemis further described, infra. After the inductor/capacitor processing,the three phases of processed power, corresponding to U1, V1, and W1 aredenoted U2, V2, and W2, respectively. The power is subsequently outputas the processed and/or filtered power 150. Additional elements of thepower processing system 100, in terms of the inductor 230, a coolingsystem 240, and mounting of the capacitors 250, are further describedinfra.

Isolators

Referring still to FIG. 2 and now to FIG. 3 , in the power processingsystem 100, the inductor 230 is optionally mounted, directly orindirectly, to a base plate 210 via a mount 236, via an inductorisolator 320, and/or via a mounting plate 284. Preferably, the inductorisolator 320 is used to attach the mount 236 indirectly to the baseplate 210. The inductor 230 is additionally preferably mounted using across-member or clamp bar 234 running through a central opening 310 inthe inductor 230 which is clamped to the base plate 210 via ties 315.The capacitor 250 is preferably similarly mounted with a capacitorisolator 325 to the base plate 210. The isolators 320, 325 arepreferably vibration, shock, and/or temperature isolators. The isolators320, 325 are preferably a glass-reinforced plastic, a glassfiber-reinforced plastic, a fiber reinforced polymer made of a plasticmatrix reinforced by fine fibers made of glass, and/or a fiberglassmaterial, such as a Glastic® (Rochling Glastic Composites, Ohio)material.

Cooling System

Referring still to FIG. 2 and now to FIG. 4 , an optional cooling system240 is used in the power processing system 100. In the illustratedembodiment, the cooling system 240 uses a fan to move air across theinductor 230. The fan either pushes or pulls an air flow around andthrough the inductor 230. An optional air guide shroud 450 is placedover 1, 2, 3, or more inductors 230 to facilitate focused air movementresultant from the cooling system 240, such as airflow from a fan,around the inductors 230. The shroud preferably encompasses at leastthree sides of the one or more inductors. To achieve enhanced cooling,the inductor is preferably mounted on an outer face 416 of the toroid.For example, the inductor 230 is mounted in a vertical orientation usingthe clamp bar 234. Vertical mounting of the inductor is furtherdescribed, infra. Optional liquid based cooling systems 240 are furtherdescribed, infra.

Buss Bars

Referring again to FIG. 2 and FIG. 3 , in the power processing system100, the capacitor 250 is preferably an array of capacitors connected inparallel to achieve a specific capacitance for each of the multi-phasesof the power supply 110. In FIG. 2 , two capacitors 250 are illustratedfor each of the multi-phased power supply U1, V1, and W1. The capacitorsare mounted using a series of busbars or buss bars 260. A buss bar 260carries power from one point to another or connects one point toanother.

Common Neutral Buss bar

A particular type of buss bar 260 is a common neutral buss bar 265,which connects two phases. In one example of an electrical embodiment ofa delta capacitor connection in a poly phase system, it is preferable tocreate a common neutral point for the capacitors. Still referring toFIG. 2 , an example of two phases using multiple capacitors in parallelwith a common neutral buss bar 265 is provided. The common neutral bussbar 265 functions as both a mount and a parallel bus conductor for twophases. This concept minimizes the number of parallel conductors, in a‘U’ shape or in a parallel ‘| |’ shape in the present embodiment, to thenumber of phases plus two. In a traditional parallel buss bar system,the number of buss bars 260 used is the number of phases multiplied bytwo or number of phases times two. Hence, the use of ‘U’ shaped bussbars 260 reduces the number of buss bars used compared to thetraditional mounting system. Minimizing the number of buss bars requiredto make a poly phase capacitor assembly, where multiple smallercapacitors are positioned in parallel to create a larger capacitance,minimizes the volume of space needed and the volume of buss barconductors. Reduction in buss bar 260 volume and/or quantity minimizescost of the capacitor assembly. After the two phases that share a commonneutral bus conductor are assembled, a simple jumper 270 bus conductoris optionally used to jumper those two phases to any quantity ofadditional phases as shown in FIG. 2 . The jumper optionally includes aslittle as two connection points. The jumper optionally functions as ahandle on the capacitor assembly for handling. It is also typical thatthis common neutral bus conductor is the same shape as the otherparallel bus conductors throughout the capacitor assembly. This commonshape theme, a ‘U’ shape in the present embodiment, allows for symmetryof the assembly in a poly phase structure as shown in FIG. 2 .

Parallel Buss Bars Function as Mounting Chassis

Herein, the buss bars 260, 265 preferably mechanically support thecapacitors 250. The use of the buss bars 260, 265 for mechanical supportof the capacitors 250 has several benefits. The parallel conducting bussbar connecting multiple smaller value capacitors to create a largervalue, which can be used in a ‘U’ shape, also functions as a mountingchassis. Incorporating the buss bar as a mounting chassis removes therequirement of the capacitor 250 to have separate, isolated mountingbrackets. These brackets typically would mount to a ground point ormetal chassis in a filter system. In the present embodiment, thecapacitor terminals and the parallel buss bar support the capacitors andeliminate the need for expensive mounting brackets and additionalmounting hardware for these brackets. This mounting concept allows foroptimal vertical or horizontal packaging of capacitors.

Parallel Buss Bar

A parallel buss bar is optionally configured to carry smaller currentsthan an input/output terminal. The size of the buss bar 260 is minimizeddue to its handling of only the capacitor current and not the total linecurrent, where the capacitor current is less than about 10, 20, 30, or40 percent of the total line current. The parallel conducting buss bar,which also functions as the mounting chassis, does not have to conductfull line current of the filter. Hence the parallel conducting buss baris optionally reduced in cross-section area when compared to the outputterminal 350. This smaller sized buss bar reduces the cost of theconductors required for the parallel configuration of the capacitors byreducing the conductor material volume. The full line current that isconnected from the inductor to the terminal is substantially larger thanthe current that travels through the capacitors. For example, thecapacitor current is less than about 10, 20, 30, or 40 percent of thefull line current. In addition, when an inductor is used that impedesthe higher frequencies by about 20, 100, 200, 500, 1000, 1500, or 2000KHz before they reach the capacitor buss bar and capacitors, thisparallel capacitor current is lower still than when an inferior filterinductor, whose resonant frequency is below 5, 10, 20, 40, 50, 75, 100KHz, is used which cannot impede the higher frequencies due to its highinternal capacitive construction or low resonant frequency. In caseswhere there exist high frequency harmonics and the inductor is unable toimpede these high frequencies, the capacitors must absorb and filterthese currents which causes them to operate at higher temperatures,which decreases the capacitors usable life in the circuit. In addition,these un-impeded frequencies add to the necessary volume requirement ofthe capacitor buss bar and mounting chassis, which increases cost of thepower processing system 100.

Staggered Capacitor Mounting

Use of a staggered capacitor mounting system reduces and/or minimizesvolume requirements for the capacitors.

Referring now to FIG. 3 , a filter system 300 is illustrated. The filtersystem 300 preferably includes a mounting plate or base plate 210. Themounting plate 210 attaches to the inductor 230 and a set of capacitors330. The capacitors are preferably staggered in an about close packedarrangement having a spacing between rows and staggered columns of lessthan about 0.25, 0.5, or 1 inch. The staggered packaging allows optimumpackaging of multiple smaller value capacitors in parallel creating alarger capacitance in a small, efficient space.

Buss bars 260 are optionally used in a ‘U’ shape or a parallel ‘| |’shape to optimize packaging size for a required capacitance value. The‘U’ shape with staggered capacitors 250 are optionally mountedvertically to the mounting surface, as shown in FIG. 3 or horizontallyto the mounting surface as shown in FIG. 15 . The ‘U’ shape buss bar isoptionally two about parallel bars with one or more optional mechanicalstabilizing spacers, 267, at selected locations to mechanicallystabilize both about parallel sides of the ‘U’ shape buss bar as thebuss bar extends from the terminal 350, as shown in FIG. 3 and FIG. 15 .

In this example, the capacitor bus work 260 is in a ‘U’ shape thatfastens to a terminal 350 attached to the base plate 210 via aninsulator 325. The ‘U’ shape is formed by a first buss bar 260 joined toa second buss bar 260 via the terminal 350. The ‘U’ shape isalternatively shaped to maintain the staggered spacing, such as with anm by n array of capacitors, where m and n are integers, where m and nare each two or greater. The buss bar matrix or assembly containsneutral points 265 that are preferably shared between two phases of apoly-phase system. The neutral buss bars 260, 265 connect to allthree-phases via the jumper 270. The shared buss bar 265 allows thepoly-phase system to have x+2 buss bars where x is the number of phasesin the poly-phase system instead of the traditional two buss bars perphase in a regular system. Optionally, the common buss bar 265 comprisesa metal thickness of approximately twice the size of the buss bar 260.The staggered spacing enhances packaging efficiency by allowing amaximum number of capacitors in a given volume while maintaining aminimal distance between capacitors needed for the optional coolingsystem 240, such as cooling fans and/or use of a coolant fluid. Use of acoolant fluid directly contacting the inductor 230 is described, infra.The distance from the mounting surface 210 to the bottom or closestpoint on the body of the second closest capacitor 250, is less than thedistance from the mounting surface 210 to the top or furthest point onthe body of the closest capacitor. This mounting system is designated asa staggered mounting system for parallel connected capacitors in asingle or poly phase filter system.

Module Mounting

In the power processing system 100, modular components are optionallyused. For example, a first mounting plate 280 is illustrated that mountsthree buss bars 260 and two arrays of capacitors 250 to the base plate210. A second mounting plate 282 is illustrated that mounts a pair ofbuss bars 260 and a set of capacitors to the base plate 210. A thirdmounting plate 284 is illustrated that vertically mounts an inductor andoptionally an associated cooling system 240 or fan to the base plate210. Generally, one or more mounting plates are used to mount anycombination of inductor 230, capacitor 240, buss bar 260, and/or coolingsystem 240 to the base plate 210.

Referring now to FIG. 3 , an additional side view example of a powerprocessing system 100 is illustrated. FIG. 3 further illustrates avertical mounting system 305 for the inductor 230 and/or the capacitor250. For clarity, the example illustrated in FIG. 3 shows only a singlephase of a multi-phase power filtering system. Additionally, wiringelements are removed in FIG. 3 for clarity. Additional inductor 230 andcapacitor 250 detail is provided, infra.

Inductor

Preferable embodiments of the inductor 230 are further described herein.Particularly, in a first section, vertical mounting of an inductor isdescribed. In a second section, inductor elements are described.

For clarity, an axis system is herein defined relative to an inductor230. An x/y plane runs parallel to an inductor face 417, such as theinductor front face 418 and/or the inductor back face 419. A z-axis runsthrough the inductor 230 perpendicular to the x/y plane. Hence, the axissystem is not defined relative to gravity, but rather is definedrelative to an inductor 230.

Vertical Inductor Mounting

FIG. 3 illustrates an indirect vertical mounting system of the inductor230 to the base plate 210 with an optional intermediate vibration,shock, and/or temperature isolator 320. The isolator 320 is preferably aGlastic© material, described supra. The inductor 230 is preferably anedge mounted inductor with a toroidal core, described infra.

Referring now to FIG. 6A, an inductor 230 optionally includes aninductor core 610 and a winding 620. The winding 620 is wrapped aroundthe inductor core 610. The inductor core 610 and the winding 620 aresuitably disposed on a base plate 210 to support the inductor core 610in any suitable position and/or to conduct heat away from the inductorcore 610 and the winding 620. The inductor 610 optionally includes anyadditional elements or features, such as other items required inmanufacturing.

Referring now to FIG. 6B, an inductor core of the inductor 230optionally and preferably comprises a distributed gap material of coatedparticles 630 than have alternating magnetic layers 632 andsubstantially non-magnetic layers 634, where the coated particles 630are separated by an average distance, d₁.

In one embodiment, an inductor 230 or toroidal inductor is mounted onthe inductor edge, is vibration isolated, and/or is optionallytemperature controlled. Referring now to FIG. 4 and FIG. 5 , an exampleof an edge mounted inductor system 400 is illustrated. FIG. 4illustrates an edge mounted toroidal inductor 230 from a face view. FIG.5 illustrates the inductor 230 from an edge view.

When looking through a center hole 412 of the inductor 230, the inductor230 is viewed from its face. When looking at the inductor 230 along anaxis-normal to an axis running through the center hole 412 of theinductor 230, the inductor 230 is viewed from the inductor edge. In anedge mounted inductor system, the edge of the inductor is mounted to asurface. In a face mounted inductor system, the face of the inductor 230is mounted to a surface. Elements of the edge mounted inductor system400 are described, infra.

Referring still to FIG. 4 , the inductor 230 is optionally mounted in avertical orientation, where a center line through the center hole 412 ofthe inductor runs along an axis 405 that is about horizontal or parallelto a mounting surface 430 or base plate 210. The mounting surface isoptionally horizontal or vertical, such as parallel to a floor, parallelto a wall, or parallel to a mounting surface on a slope.

In FIG. 4 , the inductor 230 is illustrated in a vertical positionrelative to a horizontal mounting surface with the axis 405 runningparallel to a floor. While descriptions herein use a horizontal mountingsurface to illustrate the components of the edge mounted inductormounting system 400, the system is equally applicable to a verticalmounting surface. To further clarify, the edge mounted inductor system400 described herein also applies to mounting the edge of the inductorto a vertical mounting surface or an angled mounting surface. The angledmounting surface is optionally angled at least 10, 20, 30, 40, 50, 60,70, or 80 degrees off of horizontal. In these cases, the axis 405 stillruns about parallel to the mounting surface, such as about parallel tothe vertical mounting surface or about parallel to a sloped mountingsurface 430, base plate 210, or other surface.

Still referring to FIG. 4 and to FIG. 5 , the inductor 230 has an innersurface 414 surrounding the center opening, center aperture, or centerhole 412; an outer edge 416 or outer edge surface; and two faces 417,including a front face 418 and a back face 419. An inductor sectionrefers to a portion of the about annular inductor between a point on theinner surface 414 and a closest point on the outer edge 416. The surfaceof the inductor 230 includes: the inner surface 414, outer edge 416 orouter edge surface, and faces 417. The surface of the inductor 230 istypically the outer surface of the magnet wire windings surrounding thecore of the inductor 230. Magnet wire or enameled wire is a copper oraluminium wire coated with a very thin layer of insulation. In one case,the magnet wire comprises a fully annealed electrolytically refinedcopper. In another case, the magnet wire comprises aluminum magnet wire.In still another case, the magnet wire comprises silver or anotherprecious metal to further enhance current flow while reducing operatingtemperatures. Optionally, the magnet wire has a cross-sectional shapethat is round, square, and/or rectangular. A preferred embodiment usesrectangular magnet wire to wind the annular inductor to increase currentflow in the limited space in a central aperture within the inductorand/or to increase current density. The insulation layer includes 1, 2,3, 4, or more layers of an insulating material, such as a polyvinyl,polyimide, polyamide, and/or fiberglass based material. The magnet wireis preferably a wire with an aluminum oxide coating for minimal coronapotential. The magnet wire is preferably temperature resistant or ratedto at least two hundred degrees Centigrade. The winding of the wire ormagnet wire is further described, infra. The minimum weight of theinductor is optionally about 2, 5, 10, or 20 pounds.

Still referring to FIG. 4 , an optional clamp bar 234 runs through thecenter hole 412 of the inductor 230. The clamp bar 234 is preferably asingle piece, but is optionally composed of multiple elements. The clampbar 234 is connected directly or indirectly to the mounting surface 430and/or to a base plate 210. The clamp bar 234 is composed of anon-conductive material as metal running through the center hole of theinductor 230 functions as a magnetic shorted turn in the system. Theclamp bar 234 is preferably a rigid material or a semi-rigid materialthat bends slightly when clamped, bolted, or fastened to the mountingsurface 430. The clamp bar 234 is preferably rated to a temperature ofat least 130 degrees Centigrade. Preferably, the clamp bar material is afiberglass material, such as a thermoset fiberglass-reinforced polyestermaterial, that offers strength, excellent insulating electricalproperties, dimensional stability, flame resistance, flexibility, andhigh property retention under heat. An example of a fiberglass clamp barmaterial is Glastic©. Optionally the clamp bar 234 is a plastic, a fiberreinforced resin, a woven paper, an impregnated glass fiber, a circuitboard material, a high performance fiberglass composite, a phenolicmaterial, a thermoplastic, a fiberglass reinforced plastic, a ceramic,or the like, which is preferably rated to at least 150 degreesCentigrade. Any of the mounting hardware 422 is optionally made of thesematerials.

Still referring to FIG. 4 and to FIG. 5 , the clamp bar 234 ispreferably attached to the mounting surface 430 via mounting hardware422. Examples of mounting hardware include: a bolt, a threaded bolt, arod, a clamp bar 234, a mounting insulator 424, a connector, a metalconnector, and/or a non-metallic connector. Preferably, the mountinghardware is non-conducting. If the mounting hardware 422 is conductive,then the mounting hardware 422 is preferably contained in or isolatedfrom the inductor 230 via a mounting insulator 424. Preferably, anelectrically insulating surface is present, such as on the mountinghardware. The electrically insulating surface proximately contacts thefaces of the inductor 230. Alternatively, an insulating gap 426 of atleast about one millimeter exists between the faces 417 of the inductor230 and the metallic or insulated mounting hardware 422, such as a boltor rod.

An example of a mounting insulator is a hollow rod where the outersurface of the hollow rod is non-conductive and the hollow rod has acenter channel 425 through which mounting hardware, such as a threadedbolt, runs. This system allows a stronger metallic and/or conductingmounting hardware to connect the clamp bar 234 to the mounting surface430. FIG. 5 illustrates an exemplary bolt head 423 fastening a threadedbolt into the base plate 210 where the base plate has a threaded hole.An example of a mounting insulator 424 is a mounting rod. The mountingrod is preferably composed of a material or is at least partiallycovered with a material where the material is electrically isolating.

The mounting hardware 422 preferably covers a minimal area of theinductor 230 to facilitate cooling with a cooling element 240, such asvia one or more fans. In one case, the mounting hardware 422 does notcontact the faces 417 of the inductor 230. In another case, the mountinghardware 422 contacts the faces 417 of the inductor 230 with a contactarea. Preferably the contact area is less than about 1, 2, 5, 10, 20, or30 percent of the surface area of the faces 417. The minimal contactarea of the mounting hardware with the inductor surface facilitatestemperature control and/or cooling of the inductor 230 by allowingairflow to reach the majority of the inductor 230 surface. Preferably,the mounting hardware is temperature resistant to at least 130 degreescentigrade. Preferably, the mounting hardware 422 comprises curvedsurfaces circumferential about its length to facilitate airflow aroundthe length of the mounting hardware 422 to the faces 417 of the inductor230.

Still referring to FIG. 5 , the mounting hardware 422 connects the clampbar 234, which passes through the inductor, to the mounting surface 430.The mounting surface is optionally non-metallic and is rigid orsemi-rigid. Generally, the properties of the clamp bar 234 apply to theproperties of the mounting surface 430. The mounting surface 430 isoptionally (1) composed of the same material as the clamp bar 234 or is(2) a distinct material type from that of the clamp bar 234.

Still referring to FIG. 5 , in one example the inductor 230 is held in avertical position by the clamp bar 234, mounting hardware 422, andmounting surface 430 where the clamp bar 234 contacts the inner surface414 of the inductor 230 and the mounting surface 430 contacts the outeredge 416 of the inductor 230.

Still referring to FIG. 5 , in a second example one or more vibrationisolators 440 are used in the mounting system. As illustrated, a firstvibration isolator 440 is positioned between the clamp bar 234 and theinner surface 414 of the inductor 230 and a second vibration isolator440 is positioned between the outer edge 416 of the inductor 230 and themounting surface 430. The vibration isolator 440 is a shock absorber.The vibration isolator optionally deforms under the force or pressurenecessary to hold the inductor 230 in a vertical position or edgemounted position using the clamp bar 234, mounting hardware 422, andmounting surface 430. The vibration isolator preferably is temperaturerated to at least two hundred degrees Centigrade. Preferably thevibration isolator 440 is about ⅛, ¼, ⅜, or ½ inch in thickness. Anexample of a vibration isolator is silicone rubber. Optionally, thevibration isolator 440 contains a glass weave 442 for strength. Thevibration isolator optionally is internal to the inductor opening orextends out of the inductor 230 central hole 412.

Still referring to FIG. 5 , a common mounting surface 430 is optionallyused as a mount for multiple inductors. Alternatively, the mountingsurface 430 is connected to a base plate 210. The base plate 210 isoptionally used as a base for multiple mounting surfaces connected tomultiple inductors, such as three inductors used with a poly-phase powersystem where one inductor handles each phase of the power system. Thebase plate 210 optionally supports multiple cooling elements, such asone or more cooling elements per inductor. The base plate is preferablymetal for strength and durability. The system reduces cost associatedwith the mounting surface 430 as the less expensive base plate 210 isused for controlling relative position of multiple inductors and theamount of mounting surface 430 material is reduced and/or minimized.Further, the contact area ratio of the mounting surface 430 to theinductor surface is preferably minimized, such as to less than about 1,2, 4, 6, 8, 10, or 20 percent of the surface of the inductor 230, tofacilitate efficient heat transfer by maximizing the surface area of theinductor 230 available for cooling by the cooling element 240 or bypassive cooling.

Still referring to FIG. 4 , an optional cooling system 240 is used tocool the inductor. In one example, a fan blows air about one direction,such as horizontally, onto the front face 418, through the center hole412, along the inner edge 414 of the inductor 230, and/or along theouter edge 416 of the inductor 230 where the clamp bar 234, vibrationisolator 440, mounting hardware 422, and mounting surface 430 combinedcontact less than about 1, 2, 5, 10, 20, or 30 percent of the surfacearea of the inductor 230, which yields efficient cooling of the inductor230 using minimal cooling elements and associated cooling element powerdue to a large fraction of the surface area of the inductor 230 beingavailable for cooling. To aid cooling, an optional shroud 450 about theinductor 230 guides the cooling air flow about the inductor 230 surface.The shroud 450 optionally circumferentially encloses the inductor along1, 2, 3, or 4 sides. The shroud 450 is optionally any geometric shape.

Preferably, mounting hardware 422 is used on both sides of the inductor230. Optionally, the inductor 230 mounting hardware 422 is used besideonly one face of the inductor 230 and the clamp bar 234 or equivalentpresses down or hooks over the inductor 230 through the hole 412 or overthe entire inductor 230, such as over the top of the inductor 230.

In yet another embodiment, a section or row of inductors 230 areelevated in a given airflow path. In this layout, a single airflow pathor thermal reduction apparatus is used to cool a maximum number oftoroid filter inductors in a filter circuit, reducing additional fans orthermal management systems required as well as overall packaging size.This increases the robustness of the filter with fewer moving parts todegrade as well as minimizes cost and packaging size. The elevatedlayout of a first inductor relative to a second inductor allows air tocool inductors in the first row and then to also cool inductors in anelevated rear row without excessive heating of the air from the frontrow and with a single airflow path and direction from the thermalmanagement source. Through elevation, a single fan is preferably used tocool a plurality of inductors approximately evenly, where multiple fanswould have been needed to achieve the same result. This efficientconcept drastically reduces fan count and package size and allows forcooling airflow in a single direction.

An example of an inductor mounting system is provided. Preferably, thepedestal or non-planar base plate, on which the inductors are mounted,is made out of any suitable material. In the current embodiment, thepedestal is made out of sheet metal and fixed to a location behind andabove the bottom row of inductors. Multiple orientations of the pedestaland/or thermal management devices are similarly implemented to achievethese results. In this example, toroid inductors mounted on the pedestaluse a silicone rubber shock absorber mounting concept with a bottomplate, base plate, mounting hardware 122, a center hole clamp bar withinsulated metal fasteners, or mounting hardware 122 that allows them tobe safe for mounting at this elevated height. The mounting conceptoptionally includes a non-conductive material of suitable temperatureand mechanical integrity, such as Glastic©, as a bottom mounting plate.The toroid sits on a shock absorber of silicone rubber material ofsuitable temperature and mechanical integrity. In this example, thevibration isolator 440, such as silicone rubber, is about 0.125 inchthick with a woven fiber center to provide mechanical durability to themounting. The toroid is held in place by a center hole clamp bar ofGlastic® or other non-conductive material of suitable temperature andmechanical integrity. The clamp bar fits through the center hole of thetoroid and preferably has a minimum of one hole on each end, two totalholes, to allow fasteners to fasten the clamp bar to the bottom plateand pedestal or base plate. Beneath the center clamp bar is anothershock absorbing piece of silicone rubber with the same properties as thebottom shock absorbing rubber. The clamp bar is torqued down on bothsides using fasteners, such as standard metal fasteners. The fastenersare preferably an insulated non-conductive material of suitabletemperature and mechanical integrity. The mounting system allows formounting of the elevated pedestal inductors with the center holeparallel to the mounting chassis and allows the maximum surface area ofthe toroid to be exposed to the moving air, thus maximizing theefficiency of the thermal management system. In addition, this mountingsystem allows for the two shock absorbing rubber or equivalent materialsto both hold the toroid inductor in an upright position. The shockabsorbing material also absorbs additional shock and vibration resultingduring operation, transportation, or installation so that core materialshock and winding shock is minimized.

Inductor Elements

The inductor 230 is further described herein. Preferably, the inductorincludes a pressed powder highly permeable and linear core having a BHcurve slope of about 11 ΔB/ΔH surrounded by windings and/or anintegrated cooling system.

Referring now to FIG. 6 , the inductor 230 comprises a inductor core 610and a winding 620. The inductor 230 preferably includes any additionalelements or features, such as other items required in manufacturing. Thewinding 620 is wrapped around the inductor core 610. The inductor core610 provides mechanical support for the winding 620 and is characterizedby a permeability for storing or transferring a magnetic field inresponse to current flowing through the winding 620. Herein,permeability is defined in terms of a slope of AB/AH. The inductor core610 and winding 620 are suitably disposed on or in a mount or housing210 to support the inductor core 610 in any suitable position and/or toconduct heat away from the inductor core 610 and the winding 620.

The inductor core optionally provides mechanical support for theinductor winding and comprises any suitable core for providing thedesired magnetic permeability and/or other characteristics. Theconfiguration and materials of the inductor core 610 are optionallyselected according to any suitable criteria, such as a BH curve profile,permeability, availability, cost, operating characteristics in variousenvironments, ability to withstand various conditions, heat generation,thermal aging, thermal impedance, thermal coefficient of expansion,curie temperature, tensile strength, core losses, and/or compressionstrength. For example, the inductor core 610 is optionally configured toexhibit a selected permeability and BH curve.

For example, the inductor core 610 is configured to exhibit low corelosses under various operating conditions, such as in response to a highfrequency pulse width modulation or harmonic ripple, compared toconventional materials. Conventional core materials are laminatedsilicon steel or conventional silicon iron steel designs. The inventorhas determined that the core preferably comprises an iron powdermaterial or multiple materials to provide a specific BH curve, describedinfra. The specified BH curve allows creation of inductors having:smaller components, reduced emissions, reduced core losses, andincreased surface area in a given volume when compared to inductorsusing the above described traditional materials.

BH Curve

There are two quantities that physicists use to denote magnetic field, Band H. The vector field, H, is known among electrical engineers as themagnetic field intensity or magnetic field strength, which is also knownas an auxiliary magnetic field or a magnetizing field. The vector field,H, is a function of applied current.

The vector field, B, is known as magnetic flux density or magneticinduction and has the international system of units (SI units) of Teslas(T). Thus, a BH curve is induction, B, as a function of the magneticfield, H.

Inductor Core/Distributed Gap

In one exemplary embodiment, the inductor core 610 comprises at leasttwo materials. In one example, the core includes two materials, amagnetic material and a coating agent. In one case, the magneticmaterial includes a first transition series metal in elemental formand/or in any oxidation state. In a second case, the magnetic materialis a form of iron. The second material is optionally a non-magneticmaterial and/or is a highly thermally conductive material, such ascarbon, a carbon allotrope, and/or a form of carbon. A form of carbonincludes any arrangement of elemental carbon and/or carbon bonded to oneor more other types of atoms.

In one case, the magnetic material is present as particles and theparticles are each coated with the coating agent to form coatedparticles. For example, particles of the magnetic material are eachsubstantially coated with one, two, three, or more layers of a coatingmaterial, such as a form of carbon. The carbon provides a shock absorberaffect, which minimized high frequency core loss from the inductor 230.In a preferred embodiment, particles of iron, or a form thereof, arecoated with multiple layers of carbon to form carbon coated particles.The coated particles are optionally combined with a filler, such as athermosetting polymer or an epoxy. The filler provides an average gapdistance between the coated particles.

In another case, the magnetic material is present as a first layer inthe form of particles and the particles are each at least partiallycoated, in a second layer, with the coating agent to form coatedparticles. The coated particles 630 are subsequently coated with anotherlayer of a magnetic material, which is optionally the first magneticmaterial, to form a three layer particle. The three layer particle isoptionally coated with a fourth layer of a non-magnetic material, whichis optionally the non-magnetic material of the second layer. The processis optionally repeated to form particles of n layers, where n is apositive integer, such as about 2, 3, 4, 5, 10, 15, or 20. The n layersoptionally alternate between a magnetic layer 632 and a non-magneticlayer 634. Optionally, the innermost particle of each coated particle isa non-magnetic particle.

Optionally, the magnetic material of one or more of the layers in thecoated particle is an alloy. In one example, the alloy contains at least70, 75, 80, 85, or 90 percent iron or a form of iron, such as iron at anoxidation state or bound to another atom. In another example, the alloycontains at least 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 percent aluminum or aform of aluminum. Optionally, the alloy contains a metalloid, such asboron, silicon, germanium, arsenic, antimony, and/or tellurium. Anexample of an alloy is sendust, which contains about eighty-five percentiron, nine percent silicon, and six percent aluminum. Sendust exhibitsabout zero magnetostriction.

The coated particles preferably have, with a probability of at leastninety percent, an average cross-sectional length of less than about onemillimeter, one-tenth of a millimeter (100 μm), and/or one-hundredth ofa millimeter (10 μm). While two or more coated particles in the core areoptionally touching, the average gap distance, d₁, 636 between twocoated particles is optionally a distance greater than zero and lessthan about one millimeter, one-tenth of a millimeter (100 μm),one-hundredth of a millimeter (10 μm), and/or one-thousandth of amillimeter (1 μm). With a large number of coated particles in theinductor 230, there exist a large number of gaps between two adjacentcoated particles that are about evenly distributed within at least aportion of the inductor. The about evenly distributed gaps betweenparticles in the inductor is optionally referred to as a distributedgap.

In one exemplary manufacturing process, the carbon coated particles aremixed with a filler, such as an epoxy. The resulting mixture isoptionally pressed into a shape, such as an inductor shape, an abouttoroidal shape, a toroid shape, an about annular shape, or an aboutdoughnut shape. Optionally, during the pressing process, the filler orepoxy is melted out. The magnetic path in the inductor goes through thedistributed gaps. Small air pockets optionally exist in the inductor230, such as between the coated particles. In use, the magnetic fieldgoes from coated particle to coated particle through the filler gapsand/or through the air gaps.

The distributed gap nature of the inductor 230 yields an about even Eddyloss, gap loss, or magnetic flux loss. Substantially even distributionof the bonding agent within the iron powder of the core results in theequally distributed gap of the core. The resultant core loss at theswitching frequencies of the electrical switches substantially reducescore losses when compared to silicon iron steel used in conventionaliron core inductor design.

Further, conventional inductor construction requires gaps in themagnetic path of the steel lamination, which are typically outside thecoil construction and are, therefore, unshielded from emitting flux,causing electromagnetically interfering radiation. The electromagneticradiation can adversely affect the electrical system.

The distributed gaps in the magnetic path of the present inductor core610 material are microscopic and substantially evenly distributedthroughout the inductor core 610. The smaller flux energy at each gaplocation is also surrounded by a winding 620 which functions as anelectromagnetic shield to contain the flux energy. Thus, a pressedpowder core surrounded by windings results in substantially reducedelectromagnetic emissions.

Referring now to FIG. 7 and to Table 1, preferred inductance, B, levelsas a function of magnetic force strength are provided. The inductor core610 material preferably comprises: an inductance of about −4400 to 4400B over a range of about −400 to 400 H with a slope of about 11 AB/AH.Herein, permeability refers to the slope of a BH curve and has units ofAB/AH. Core materials having a substantially linear BH curve with AB/AHin the range of ten to twelve are usable in a preferred embodiment. Lesspreferably, core materials having a substantially linear BH curve with apermeability, AB/AH, in the range of nine to thirteen are acceptable.Two exemplary BH curves 710, 720 are provided in FIG. 7 .

TABLE 1 BH Response (Permeability of Eleven) B H (Tesla/Gauss) (Oersted)−4400 −400 −2200 −200 −1100 −100 1100 100 2200 200 4400 400

Optionally, the inductor 230 is configured to carry a magnetic field ofat least one of:

-   -   less than about 2000, 2500, 3000, or 3500 Gauss at an absolute        Oersted value of at least 100;    -   less than about 4000, 5000, 6000, or 7000 Gauss at an absolute        Oersted value of at least 200;    -   less than about 6000, 7500, 9000, or 10,500 Gauss at an absolute        Oersted value of at least 300; and    -   less than about 8000, 10,000, 12,000, or 14,000 Gauss at an        absolute Oersted value of at least 400.

In one embodiment, the inductor core 610 material exhibits asubstantially linear flux density response to magnetizing forces over alarge range with very low residual flux, B_(R). The inductor core 610preferably provides inductance stability over a range of changingpotential loads, from low load to full load to overload.

The inductor core 610 is preferably configured in an about toroidal,about circular, doughnut, or annular shape where the toroid is of anysize. The configuration of the inductor core 610 is preferably selectedto maximize the inductance rating, A_(L), of the inductor core 610,enhance heat dissipation, reduce emissions, facilitate winding, and/orreduce residual capacitances.

Medium Voltage

Herein, a corona potential is the potential for long term breakdown ofwinding wire insulation due to high electric potentials between windingturns winding a mid-level power inductor in a converter system. The highelectric potential creates ozone, which breaks down insulation coatingthe winding wire and results in degraded performance or failure of theinductor.

Herein, power is described as a function of voltage. Typically, homesand buildings use low voltage power supplies, which range from about 100to 690 volts. Large industry, such as steel mills, chemical plants,paper mills, and other large industrial processes optionally use mediumvoltage filter inductors and/or medium voltage power supplies. Herein,medium voltage power refers to power having about 1,500 to 35,000 voltsor optionally about 2,000 to 5,000 volts. High voltage power refers tohigh voltage systems or high voltage power lines, which operate fromabout 20,000 to 150,000 volts.

In one embodiment, a power converter method and apparatus is described,which is optionally part of a filtering method and apparatus. Theinductor is configured with inductor winding spacers, such as a maininductor spacer and/or inductor segmenting winding spacers. The spacersare used to space winding turns of a winding coil about an inductor. Theinsulation of the inductor spacer minimizes energy transfer betweenwindings and thus minimizes corona potential, formation of corrosiveozone through ionization of oxygen, correlated breakdown of insulationon the winding wire, and/or electrical shorts in the inductor.

More particularly, the inductor configured with winding spacers uses thewinding spacers to separate winding turns of a winding wire about thecore of the inductor, which reduces the volts per turn. The reduction involts per turn minimizes corona potential of the inductor. Additionalelectromagnetic components, such as capacitors, are integrated with theinductor configured with winding spacers to facilitate power processingand/or power conversion. The inductors configured with winding spacersdescribed herein are designed to operate on medium voltage systems andto minimize corona potential in a mid-level power converter. Theinductors configured with winding spacers, described infra, areoptionally used on low and/or high voltage systems.

Inductor Winding Spacers

In still yet another embodiment, the inductor 230 is optionallyconfigured with inductor winding spacers. Generally, the inductorwinding spacers or simply winding spacers are used to space windingturns to reduce corona potential, described infra.

For clarity of presentation, initially the inductor winding isdescribed. Subsequently, the corona potential is further described. Thenthe inductor spacers are described. Finally, the use of the inductorspacers to reduce corona potential through controlled winding withwinding turns separated by the insulating inductor spacers is described.

Inductor Winding

The inductor 230 includes a inductor core 610 that is wound with awinding 620. The winding 620 comprises a conductor for conductingelectrical current through the inductor 230. The winding 620 optionallycomprises any suitable material for conducting current, such asconventional wire, foil, twisted cables, and the like formed of copper,aluminum, gold, silver, or other electrically conductive material oralloy at any temperature.

Preferably, the winding 620 comprises a set of wires, such as coppermagnet wires, wound around the inductor core 610 in one or more layers.Preferably, each wire of the set of wires is wound through a number ofturns about the inductor core 610, where each element of the set ofwires initiates the winding at a winding input terminal and completesthe winding at a winding output terminal. Optionally, the set of wiresforming the winding 620 nearly entirely covers the inductor core 610,such as a toroidal shaped core. Leakage flux is inhibited from exitingthe inductor 230 by the winding 620, thus reducing electromagneticemissions, as the windings 620 function as a shield against suchemissions. In addition, the soft radii in the geometry of the windings620 and the inductor core 610 material are less prone to leakage fluxthan conventional configurations. Stated again, the toroidal or doughnutshaped core provides a curved outer surface upon which the windings arewound. The curved surface allows about uniform support for the windingsand minimizes and/or reduced gaps between the winding and the core.

Corona Potential

A corona potential is the potential for long term breakdown of windingwire insulation due to the high electric potentials between windingturns near the inductor 230, which creates ozone. The ozone breaks downinsulation coating the winding wire, results in degraded performance,and/or results in failure of the inductor 230.

Inductor Spacers

The inductor 230 is optionally configured with inductor winding spacers,such as a main inductor spacer 810 and/or inductor segmenting windingspacers 820. Generally, the spacers are used to space winding turns,described infra. Collectively, the main inductor spacer 810 andsegmenting winding spacers 820 are referred to herein as inductorspacers. Generally, the inductor spacer comprises a non-conductivematerial, such as air, a plastic, or a dielectric material. Theinsulation of the inductor spacer minimizes energy transfer betweenwindings and thus minimizes or reduces corona potential, formation ofcorrosive ozone through ionization of oxygen, correlated breakdown ofinsulation on the winding wire, and/or electrical shorts in the inductor230.

A first low power example, of about 690 volts, is used to illustrateneed for a main inductor spacer 810 and lack of need for inductorsegmenting winding spacers 820 in a low power transformer. In thisexample, the inductor 230 includes a inductor core 610 wound twentytimes with a winding 620, where each turn of the winding about the coreis about evenly separated by rotating the inductor core 610 abouteighteen degrees (360 degrees/20 turns) for each turn of the winding. Ifeach turn of the winding 620 about the core results in 34.5 volts, thenthe potential between turns is only about 34.5 volts, which is not ofsufficient magnitude to result in a corona potential. Hence, inductorsegmentation winding spacers 820 are not required in a low powerinductor/conductor system. However, potential between the winding inputterminal and the winding output terminal is about 690 volts (34.5 voltstimes 20 turns). More specifically, the potential between a winding wirenear the input terminal and the winding wire near the output terminal isabout 690 volts, which can result in corona potential. To minimize thecorona potential, an insulating main inductor spacer 810 is placedbetween the input terminal and the output terminal. The insulatingproperty of the main inductor spacer 810 minimizes or prevents shorts inthe system, as described supra.

A second medium power example illustrates the need for both a maininductor spacer 810 and inductor segmenting winding spacers 820 in amedium power system. In this example, the inductor 230 includes ainductor core 610 wound 20 times with a winding 620, where each turn ofthe winding about the core is about evenly separated by rotating theinductor core 610 about 18 degrees (360 degrees/20 turns) for each turnof the winding. If each turn of the winding 620 about the core resultsin about 225 volts, then the potential between individual turns is about225 volts, which is of sufficient magnitude to result in a coronapotential. Placement of an inductor winding spacer 820 between each turnreduces the corona potential between individual turns of the winding.Further, potential between the winding input terminal and the windingoutput terminal is about 4500 volts (225 volts times 20 turns). Morespecifically, the potential between a winding wire near the inputterminal and the winding wire near the output terminal is about 4500volts, which results in corona potential. To minimize the coronapotential, an insulating main inductor spacer 810 is placed between theinput terminal and the output terminal. Since the potential betweenwinding wires near the input terminal and output terminal is larger(4500 volts) than the potential between individual turns of wire (225volts), the main inductor spacer 810 is preferably wider and/or has agreater insulation than the individual inductor segmenting windingspacers 820.

In a low power system, the main inductor spacer 810 is optionally about0.125 inch in thickness. In a mid-level power system, the main inductorspacer is preferably about 0.375 to 0.500 inch in thickness. Optionally,the main inductor spacer 810 thickness is greater than about 0.125,0.250, 0.375, 0.500, 0.625, or 0.850 inch. The main inductor spacer 810is preferably thicker, or more insulating, than the individualsegmenting winding spacers 820. Optionally, the individual segmentingwinding spacers 820 are greater than about 0.0312, 0.0625, 0.125, 0.250,0.375 inches thick. Generally, the main inductor spacer 810 has agreater thickness or cross-sectional width that yields a largerelectrically insulating resistivity versus the cross-section or width ofone of the individual segmenting winding spacers 820. Preferably, theelectrical resistivity of the main inductor spacer 810 between the firstturn of the winding wire proximate the input terminal and the terminaloutput turn proximate the output terminal is at least about 10, 20, 30,40, 50, 60, 70, 80, 90, or 100 percent greater than the electricalresistivity of a given inductor segmenting winding spacer 820 separatingtwo consecutive turns of the winding 620 about the inductor core 610 ofthe inductor 230. The main inductor spacer 810 is optionally a firstmaterial and the inductor segmenting spacers are optionally a secondmaterial, where the first material is not the same material as thesecond material. The main inductor spacer 810 and inductor segmentingwinding spacers 820 are further described, infra.

In yet another example, the converter operates at levels exceeding about2000 volts at currents exceeding about 400 amperes. For instance, theconverter operates at above about 1000, 2000, 3000, 4000, or 5000 voltsat currents above any of about 500, 1000, or 1500 amperes. Preferablythe converter operates at levels less than about 15,000 volts.

Referring now to FIG. 8 , an example of an inductor 230 configured withfour spacers is illustrated. For clarity, the main inductor spacer 810is positioned at the twelve o'clock position and the inductor segmentingwinding spacers 820 are positioned relative to the main inductor windingspacer. The clock position used herein are for clarity of presentation.The spacers are optionally present at any position on the inductor andany coordinate system is optionally used. For example, referring stillto FIG. 8 , the three illustrated inductor segmenting winding spacers820 are positioned at about the three o'clock, six o'clock, and nineo'clock positions. However, the main inductor spacer 810 is optionallypresent at any position and the inductor segmenting winding spacers 820are positioned relative to the main inductor spacer 810. As illustrated,the four spacers segment the toroid into four sections. Particularly,the main inductor spacer 810 and the first inductor segmenting windingspacer at the three o'clock position create a first inductor section831. The first of the inductor segmenting winding spacers at the threeo'clock position and a second of the inductor segmenting winding spacersat the six o'clock position create a second inductor section 832. Thesecond of the inductor segmenting winding spacers at the six o'clockposition and a third of the inductor segmenting winding spacers at thenine o'clock position create a third inductor section 833. The third ofthe inductor segmenting winding spacers at the nine o'clock position andthe main inductor spacer 810 at about the twelve o'clock position createa fourth inductor section 834. In this system, preferably a first turnof the winding 620 wraps the inductor core 610 in the first inductorsection 831, a second turn of the winding 620 wraps the inductor core610 in the second inductor section 832, a third turn of the winding 620wraps the inductor core 610 in the third inductor section 833, and afourth turn of the winding 620 wraps the inductor core 610 in the fourthinductor section 834. Generally, the number of inductor spacers 810 isset to create 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,18, 19, 20, or more inductor sections. Generally, the angle theta is theangle between two inductor sections from a central point 401 of theinductor 230. Each of the spacers 810, 820 is optionally a ring aboutthe inductor core 610 or is a series of segments about forming acircumferential ring about the inductor core 610.

Inductor spacers provide an insulating layer between turns of thewinding. Still referring to FIG. 8 , an individual spacer 810, 820preferably circumferentially surrounds the inductor core 610.Preferably, the individual spacers 810, 820 extend radially outwardlyfrom an outer surface of the inductor core 610. The spacers 810, 820optionally contact and/or proximally contact the inductor core 610, suchas via an adhesive layer or via a spring loaded fit.

Referring now to FIG. 9 , optionally one or more of the spacers do notentirely circumferentially surround the inductor core 610. For example,short spacers 920 separate the individual turns of the winding at leastin the central aperture 412 of the inductor core 610. In the illustratedexample, the short spacers 920 separate the individual turns of thewinding in the central aperture 412 of the inductor core 610 and along aportion of the inductor faces 417, where geometry dictates that thedistance between individual turns of the winding 620 is small relativeto average distance between the wires at the outer face 416.

Referring now to FIGS. 10, 11, and 12 , an example of an inductor 230segmented into six sections using a main inductor spacer 810 and a setof inductor segmenting winding spacers 820 is provided. Referring now toFIG. 10 , the main inductor spacer 810 and five inductor segmentingwinding spacers 820 segment the periphery of the core into six regions1031, 1032, 1033, 1034, 1035, and 1036.

Referring now to FIG. 11 , two turns of a first winding are illustrated.A first winding wire 1140 is wound around the first region core 1031 ina first turn, such as a first wire turn 1141. Similarly, the winding 620is continued in a second turn, such as a second wire turn 1142 about asecond region of the core 1032. The first wire turn 1141 and the secondwire turn 1142 are optionally separated by a first segmenting windingspacer 1132.

Referring now to FIG. 12 , six turns of a first winding are illustrated.Continuing from FIG. 11 , the winding 620 is continued in a third turn,such as a third wire turn 1143; a fourth turn, such as a fourth wireturn 1144; a fifth turn, such as a fifth wire turn 1145; and a sixthturn, such as a sixth wire turn 1146. As illustrated, optionalsegmenting spacers are used to separate turns. The first and second wireturns 1141, 1142 are separated by the first segmenting winding spacer1132, the second and third wire turns 1142, 1143 are separated by thesecond segmenting winding spacer 1133, the third and fourth wire turns1143, 1144 are separated by the third segmenting winding spacer 1134,the fourth and fifth wire turns 1144, 1145 are separated by the fourthsegmenting winding spacer 1135, and the fifth and sixth wire turns 1145,1146 are separated by the fifth segmenting winding spacer 1136. Further,the first and sixth wire turns 1141, 1146 are separated by the maininductor spacer 810. Similarly, the first two turns 1151, 1152 of asecond winding wire 1150 are illustrated, that are separated by thefirst segmenting winding spacer 1132. Generally, any number of windingwires are wrapped or layered to form the winding 620 about the inductorcore 610 of the inductor 230. An advantage of the system is that in agiven inductor section, such as the first inductor section 1031, each ofthe winding wires are at about the same potential, which yieldsessentially no risk of corona potential within a given inductor section.Generally, an m^(th) turn of an n^(th) wire are within about 5, 10, 15,30, 45, or 60 degrees of each other at any position on the inductor,such as at about the six o'clock position.

For a given winding wire, the first turn of the winding wire, such asthe first wire turn 1141, proximate the input terminal is referred toherein as an initial input turn. For the given wire, the last turn ofthe wire before the output terminal, such as the sixth wire turn 1146,is referred to herein as the terminal output turn. The initial inputturn and the terminal output turn are preferably separated by the maininductor spacer.

A given inductor segmenting winding spacer 820 optionally separates twoconsecutive winding turns of a winding wire winding the inductor core610 of the inductor 230.

Referring now to FIG. 13 , one embodiment of manufacture rotates theinductor core 610 as one or more winding wires are wrapped about theinductor core 610.

For example, for a four turn winding, the core is rotated about 90degrees with each turn. During the winding process, the inductor core610 is optionally rotated at an about constant rate or is rotated andstopped with each turn. To aid in the winding process, the spacers areoptionally tilted, rotated, or tilted and rotated.

Referring now to FIG. 13 , inductor spacers 810, 820 are illustratedthat are tilted relative to a spacer about parallel to the outer face416 of the inductor 230. For clarity of presentation, the inductorspacers are only illustrated on the outer edge of the inductor core 610.Tilted spacers on the outer edge of the inductor 230 have a length thatis aligned with the z-axis, but are tilted along the x- and/or y-axes.More specifically, as the spacer 810, 820 extends radially outward fromthe inductor core 610, the spacer 810, 820 position changes in terms ofboth the x- and y-axes locations. Referring now to FIG. 14 , inductorspacers are illustrated that are both tilted and rotated. For clarity ofpresentation, the inductor spacers are only illustrated on the outeredge of the inductor core 610. Tilted and rotated spacers on the outeredge of the inductor core 610 have both a length that is rotatedrelative to the z-axis and a height that is tilted relative to the x-and/or y-axes, as described supra.

Capacitor

Referring again to FIG. 2 , capacitors 250 are used with inductors 230to create a filter to remove harmonic distortion from current andvoltage waveforms. A buss bar carries power from one point to another.The capacitor buss bar 260 mounting system minimizes space requirementsand optimizes packaging. The buss bars use a toroid/heat sink integratedsystem solution, THISS®, (CTM Magnetics, Tempe, AZ) to filter outputpower 150 and customer generated input power 154. The efficient filteroutput terminal layout described herein minimizes the copper crosssection necessary for the capacitor buss bars 260. The copper crosssection is minimized for the capacitor buss bar by sending the bulk ofthe current directly to the output terminals 221, 223, 225. In thesecircuits, the current carrying capacity of the capacitor bus conductoris a small fraction of the full approximate line frequency load orfundamental frequency current sent to the output load via the outputterminals 221, 223, 225. The termination of the THISS® technology filterinductor is integrated to the capacitor bank for each phase of thesystem. These buss bars are optionally manufactured out of any suitablematerial and are any suitable shape. For instance, the buss bars areoptionally a flat strip or a hollow tube. In one example, flat strips oftinned copper with threaded inserts or tapped threaded holes are usedfor both mounting the capacitors mechanically as well as providingelectrical connection to each capacitor. This system optimizes thepackaging efficiency of the capacitors by mounting them vertically andstaggering each capacitor from each side of the buss bar for maximumdensity in the vertical dimension. A common neutral buss bar or flexcable 265 is used between two phases to further reduce copper quantityand to minimize size. A jumper buss bar connects this common neutralpoint to another phase efficiently, such as through use of an about flatstrip of copper. Connection fittings designed to reduce radio-frequencyinterference and power loss are optionally used. The buss bars areoptionally designed for phase matching and for connecting to existingtransmission apparatus. The buss bars optionally use a mechanicalsupport spacer, 270, made from non-magnetic, non-conductive materialwith adequate thermal and mechanical properties, such as a suitableepoxy and glass combination, a Glastic® or a Garolite material. Theintegrated output terminal buss bars provide for material handling ofthe filter assembly as well as connection to the sine wave filtered loador motor. Though a three phase implementation is displayed, theimplementation is readily adapted to integrate with other power systems.

Referring now to FIG. 15 , an additional example of a capacitor bank1500 is provided. In this example, a three phase system containing fivetotal buss bars 260 including a common neutral buss bar 265 is provided.The illustrated system contains seven columns and three rows ofcapacitors 250 per phase or twenty-one capacitors per phase for each ofthree phases, U1, V1, W1. Spacers maintain separation of the componentcapacitors. A shared neutral point 270 illustrates two phases sharing asingle shared neutral bus.

Cooling

In still yet another embodiment, the inductor 230 is cooled with acooling system 240, such as with a fan, forced air, a heat sink, a heattransfer element or system, a thermal transfer potting compound, aliquid coolant, and/or a chill plate. Each of these optional coolingsystem elements are further described, infra. While, for clarity,individual cooling elements are described separately, the coolingelements are optionally combined into the cooling system in anypermutation and/or combination.

Heat Sink

A heat sink 1640 is optionally attached to any of the electricalcomponents described herein. Optionally, a heat sink 1640 or a heat sinkfin is affixed to an internal surface of a cooling element container,where the heat sink fin protrudes into an immersion coolant, animmersion fluid, and/or into a potting compound to enhance thermaltransfer away from the inductor 230 to the housing element.

Fan

In one example, a cooling fan is used to move air across any of theelectrical components, such as the inductor 230 and/or the capacitor250. The air flow is optionally a forced air flow. Optionally, the airflow is directed through a shroud 450 encompassing one, two, three ormore inductors 230. Optionally, the shroud 450 encompasses one or moreelectrical components of one, two, three or more power phases.Optionally, the shroud 450 contains an air flow guiding element betweenindividual power phases.

Thermal Grease

Any of the inductor components, such as the inductor core, inductorwinding, a coating on the inductor core, and/or a coating on theinductor winding is optionally coated with a thermal grease to enhancethermal transfer of heat away from the inductor.

Bundt Cooling System

In another example, a Bundt pan style inductor cooling system 1600 isdescribed. Referring now to FIG. 16 , a cross-section of a Bundt panstyle cooling system is provided. A first element, an inductor guide1610, optionally includes: an outer ring 1612 and/or an inner coolingsegment 1614, elements of which are joined by an inductor positioningbase 1616 to form an open inner ring having at least an outer wall. Theinductor 230 is positioned within the inner ring of the inductor guide1610 with an inductor face 417, such as the inductor front face 418,proximate the inductor positioning base 1616. The inductor guide 1610 isoptionally about joined and/or is proximate to an inductor key 1620,where the inductor guide 1610 and the inductor key 1620 combine to forman inner ring cavity for positioning of the inductor 230. The inductorkey 1620 optionally includes an outside ring 1622, a middle post 1624,and/or an inductor lid 1626.

During use, the inductor lid 1626 is proximate an inductor face 417,such as the inductor back face 419. The inductor base 1610, inductor230, and inductor lid 1620 are optionally positioned in any orientation,such as to mount the inductor 230 horizontally, vertically, or at anangle relative to gravity.

The Bundt style inductor cooling system 1600 facilitates thermalmanagement of the inductor 230. The inductor guide 1610 and/or theinductor lid 1620 is at least partially made of a thermally transmittingmaterial, where the inductor guide 1610 and/or the inductor lid 1620draws heat away from the inductor 230. A thermal transfer agent 1630,such as a thermally conductive potting compound, a thermal grease,and/or a heat transfer liquid is optionally placed between an outersurface of the inductor 230 and an inner surface of the inductor guide1610 and/or the inductor lid 1620. One or more heat sinks 1640 or heatsink fins are optionally attached to any surface of the inductor base1610 and/or the inductor lid 1620. In one case, not illustrated, theheat sink fins function as a mechanical stand under the inductor guide1610 through which air or a liquid coolant optionally flows. Moregenerally, a heat sink 1640 is optionally attached to any of theelectrical components described herein.

Potting Material

Referring now to FIGS. 17 (A-C), the potting material 1760/pottingcompound/potting agent optionally and preferably comprises one or moreof: a high thermal transfer coefficient; resistance to fissure when themass of the inductor/conductor system has a large internal temperaturechange, such as greater than about 50, 100, or 150 degrees Centigrade;flexibility so as not to fissure with temperature variations, such asgreater than 100 degrees Centigrade, in the potting mass; low thermalimpedance between the inductor 230 and heat dissipation elements;sealing characteristics to seal the inductor assembly from theenvironment such that a unit can conform to various outdoor functions,such as exposure to water and salts; and/or mechanical integrity forholding the heat dissipating elements and inductor 230 together as asingle module at high operating temperatures, such as up to about 150 or200 degrees Centigrade. Examples of potting materials include: anelectrical insulating material, a polyurethane; a urethane; a multi-parturethane; a polyurethane; a multi-component polyurethane; a polyurethaneresin; a resin; a polyepoxide; an epoxy; a varnish; an epoxy varnish; acopolymer; a thermosetting polymer; a thermoplastic; a silicone basedmaterial; Conathane® (Cytec Industries, West Peterson, NJ), such asConathane EN-2551, 2553, 2552, 2550, 2534, 2523, 2521, and EN 7-24;Insulcast® (ITW Insulcast, Roseland, NJ), such as Insulcast 333;Stycast® (Emerson and Cuming, Billerica, MA), such as Stycast 281;and/or an epoxy varnish potting compound. As described supra, theinitial potting material 1710 is optionally mixed with a heat transferagent 1720, such as silica sand or aluminum oxide. Preferableconcentration by weight of the heat transfer agent 1720 in the finalpotting material 1730 is greater than twenty and less than eightypercent by weight. For example, the potting material 1760/pottingagent/potting compound is about 25, 30, 35, 40, 45, 50, 55, 60, 65, or70 percent silica sand and/or aluminum oxide by volume, yielding apotting compound with lower thermal impedance. The heat transferenhanced potting material is further described, infra.

Heat Transfer Enhanced Potting Material

Referring again to FIG. 17A, a method of production and resultingapparatus of a heat transfer enhanced potting material 1700 isdescribed. Generally, an initial potting material 1710 is mixed with aheat transfer agent 1720 to form a final potting material 1730 about anyelectrical component, such as about an inductor of a filter circuit, asdescribed supra. Optionally and preferably, one or more of the initialpotting material 1710, the heat transfer agent 1720, final pottingmaterial 1730, and/or any mixing, transfer pipe or tubing, and/orcontainer are pre-heated or maintained at an elevated temperature tofacility mixing and movement of components of the final potting material1730 or any constituent thereof, as further described infra.

Referring again to FIG. 17B, without loss of generality, an example of asilicon dioxide enriched potting material 1750 is provided, where thesilicon dioxide is an example of the heat transfer agent 1720.Generally, a first epoxy component 1752, such as an epoxy part A, ismixed with a silicon dioxide mixture 1754 and a second epoxy component1756, such as an epoxy part B, with or without an additive 1758 to forma final potting material 1760, which is dispensed about an electricalcomponent to form a potted electrical component, such as a pottedinductor 1770.

Sand Mixture

Still referring to FIG. 17B and referring again to FIG. 17C, withoutloss of generality, the heat transfer agent 1720 is further described,where sand is the heat transfer agent 1720. A form of sand is thesilicon dioxide mixture 1754. Herein, the silicon dioxide component 1790of the silicon dioxide mixture 1754 of the final potting material 1760is used to refer to one or more of a silica mixture, silica, silicondioxide, SiO₂, and/or a synthetic silica or sand. Generally, the silicapurity in the silicon dioxide mixture 1754 is greater than 50, 60, 70,80, 90, 95, 99, or 99.5%. The silica mixture optionally contains one ormore additional components, such as iron oxide, aluminum oxide, titaniumdioxide, calcium oxide, magnesium oxide, sodium oxide, and/or potassiumoxide. However, preferably the concentration of each of the non-siliconoxides is less than 5, 4, 3, 2, 1, 0.5, or 0.2%. For example, thealuminum oxide concentration is optionally less than 2, 1, 0.5, 0.25, or0.125%. However, as aluminum oxide functions as an expensive alternativeto silicon dioxide, impurities of aluminum oxide are optionally used.Optionally and preferably, the final concentration of silicon dioxideand/or the silicon dioxide mixture 1754 in the potting material isbetween 10 and 75%, more preferably in excess of 25% and still morepreferably 30±5%, 35±5%, 40±5%, 45±5%, 50±5%, 55±5%, or 60±5% by weight.The silicon dioxide mixture constituents are optionally of any shape,such as spherical, crystalline, rounded silica, angular silica, and/orwhole grain silica. The individual silicon dioxide mixture constituentsare preferably greater than one and less than one thousand micrometersin average diameter and/or have an inner-quartile top size of less than5, 15, 30, 45, 250, 500, 1000, or 5000 micrometers. Optionally, silica,the individual silicon dioxide components 1790, and/or crystals of thesilicon dioxide mixture 1754 comprise a ninety-fifth percentile particlesize of less than 10, 20, 40, 80, 160, 320, 640, 1280, or 2560micrometers. Optional types of silica include whole grain silica, roundsilica, angular silica, and/or sub-angular grain shaped silica.Optionally, the silicon dioxide mixture 1754 is screened to selectparticle size, particle size ranges, and/or particle size distributionsprior to use.

Additive

Still referring to FIG. 17B, the additive 1758 is optionally mixed intothe potting material in place of the silicon dioxide mixture 1754 or incombination with the silicon dioxide mixture. For example, a thermaltransfer enhancing agent is optionally mixed with the potting agent toaid in heat dissipation from the inductor during use. While metal oxidesare optionally used as the additive, the metal oxides are expensive. Theinventor has discovered that silicon dioxide functions as a readilyobtainable additive that is affordable, obtainable in desired particlesizes, and functions as a heat transfer agent in the potting material.Optional additives include iron oxide, aluminum oxide, a coloring oxide,an alkaline earth, and/or a transition metal.

Referring again to FIG. 17C, the final potting material 1760 isillustrated about an inductor 230 in a housing 1780.

Heating/Mixing Process

Referring again to FIG. 17B, one or more constituents of the finalpotting material 1760 are optionally and preferably preheated, such asto greater than 80, 90, 100, 110, 120, 130, or 140 degrees Fahrenheit tofacility movement of the one or more constituents through correspondingshipping containers, storage containers, tubing, mixers, and/or pumps.Mixing of the constituents of the final potting material 1760 isoptionally and preferably performed on preheated constituents and/orduring heating. Optionally, one, many, or all of the mixing steps useone or more pumps for each constituent moving the correspondingconstituent though connection pipes, conduit, tubing, or flow lines,where the connection pipes are also optionally and preferably preheated.One or more flow meters, heated connection pipes, and/or a scales areused to control mixing ratios, where the preferred mixing ratios aredescribed supra.

For clarity of presentation and without loss of generality, an exampleof a heating/mixing process is provided. An epoxy part A, such as in a55 gallon shipping drum, is preheated to 110 degrees Fahrenheit.Optionally, during preheating, the epoxy part A is mixed through rollingof the shipping drum during heating, such as for greater than 0.1, 1, 4,8, 16, or 24 hours. The heat transfer agent 1720, such as silica, isalso optionally and preferably heated to 110 degrees Fahrenheit andmixed with the epoxy part A in a mixing container. The resulting mixedepoxy part A and silica is combined with an epoxy part B, in the mixingcontainer or a subsequent container, where again the epoxy part B isoptionally and preferably preheated, moved through a heated line using apump, and measured. Optionally, an additive is added at any step, suchas after mixing the epoxy part A and the silica and before mixing in theepoxy part B. The resulting mixture, such as the final potting mixture1760, is subsequently dispensed into a container on, under, beside,and/or about an electrical part to be contained, such as an inductor,and/or about a cooling line, as described infra.

The resulting electrical system element potted in a solid material andheat transfer agent yields an enhanced heat transfer compound as theheat transfer of the heat transfer agent 1720 and/or additive 1758exceeds that of the raw potting material 1710. For example the heattransfer of epoxy and silica are about 0.001 and 2 W/m-K, respectively.The inventor has determined that the higher heat transfer rate of theheat transfer agent enhanced potting material allows use of a smallerinductor due to the increased efficiency at reduced operatingtemperatures and that less potting material is used for the same heattransfer, both of which reduce size and cost of the electrical system.

Potted Cooling System

In still another example, a thermally potted cooling inductor coolingsystem 1800 is described. In the potted cooling system, one or moreinductors 230 are positioned within a container 1810. A thermal transferagent 1630, such as a thermally conductive potting agent is placedsubstantially around the inductor 230 inside the container 1810. Thethermally conductive potting agent is any material, compound, or mixtureused to transfer heat away from the inductor 230, such as a resin, athermoplastic, and/or an encapsulant. Optionally, one or more coolinglines 1830 run through the thermal transfer agent. The cooling lines1830 optionally wrap 1832 the inductor 230 in one or more turns to forma cooling coil and/or pass through 1834 the inductor 230 with one ormore turns. Optionally, a coolant runs through the coolant line 1830 toremove heat to a radiator 1840. The radiator is optionally attached tothe housing 1810 or is a stand-alone unit removed from the housing. Apump 1850 is optionally positioned anywhere in the system to move thecoolant sequentially through a cooling line input 1842, through thecooling line 1830 to pick up heat from the inductor 230, through acooling line output 1844, through the radiator 1840 to dissipate heat,and optionally back into the pump 1850. Generally, the thermal transferagent 1630 facilitates movement of heat, relative to air around theinductor 230, to one or more of: a heat sink 1640, the cooling line1830, to the housing 1810, and/or to the ambient environment.

Inductor Cooling Line

In yet another example, an oil/coolant immersed inductor cooling systemis provided. Referring now to FIG. 19 , an expanded view example of aliquid cooled induction system 1900 is provided. In the illustratedexample, an inductor 230 is placed into a cooling liquid container 1910.The container 1910 is preferably enclosed, but at least holds animmersion coolant. The immersion coolant is preferably in direct contactwith the inductor 230 and/or the windings of the inductor 230.Optionally, a solid heat transfer material, such as the thermallyconductive potting compound described supra, is used in place of theliquid immersion coolant. Optionally, the immersion coolant directlycontacts at least a portion of the inductor core 610 of the inductor230, such as near the input terminal and/or the output terminal.Further, the container 1910 preferably has mounting pads designed tohold the inductor 230 off of the inner surface of the container 1910 toincrease coolant contact with the inductor 230. For example, theinductor 230 preferably has feet that allow for immersion coolantcontact with a bottom side of the inductor 230 to further facilitateheat transfer from the inductor to the cooling fluid. The mounting feetare optionally placed on a bottom side of the container to facilitatecooling air flow under the container 1910.

Heat from a circulating coolant, separate from the immersion coolant, ispreferably removed via a heat exchanger. In one example, the circulatingcoolant flows through an exit path 1844, through a heat exchanger, suchas a radiator 1840, and is returned to the container 1910 via a returnpath 1842. Optionally a fan is used to remove heat from the heatexchanger. Typically, a pump 1850 is used in the circulating path tomove the circulating coolant. Still referring to FIG. 19 , the use ofthe circulating fluid to cool the inductor is further described.Optionally, the cooling line is attached to a radiator 1840 or outsideflow through cooling source. Circulating coolant optionally flowsthrough a cooling coil:

-   -   circumferentially surrounding or making at least one cooling        line turn 1920 or circumferential turn about the outer face 416        of the inductor 230 or on an inductor edge;    -   forming a path, such as an about concentrically expanding upper        ring 1930, with subsequent turns of the cooling line forming an        upper cooling surface about parallel to the inductor front face        418;    -   forming a path, such as an about concentrically expanding lower        ring 1940, with subsequent turns of the cooling line forming a        lower cooling surface about parallel to the inductor back face        419; and    -   a cooling line running through the inductor 230 using a        non-electrically conducting cooling coil or cooling coil        segment.

Optionally, the coolant flows sequentially through one or more of theexpanding upper ring 1930, the cooling line turn 1920, and the expandinglower ring 1940 or vise-versa. Optionally, parallel cooling lines runabout, through, and/or near the inductor 230.

Coolant/Inductor Contact

In yet still another example, referring now to FIG. 20 , heat istransferred from the inductor 230 to a heat transfer solution 2020directly contacting at least part of the inductor 230.

In one case, the heat transfer solution 2020 transfers heat from theinductor 230 to an inductor housing 2010. In this case, the inductorhousing 2010 radiates the heat to the surrounding environment, such asthrough a heat sink 1640.

In another case, the inductor 230 is in direct contact with the heattransfer solution 2020, such as partially or totally immersed in anon-conductive liquid coolant. The heat transfer solution 2020 absorbsheat energy from the inductor 230 and transfers a portion of that heatto a cooling line 1830 and/or a cooling coil and a coolant therein. Thecooling line 1830, through which a coolant flows runs through the heattransfer solution 2020. The coolant caries the heat out of the inductorhousing 2010 where the heat is removed from the system, such as in aheat exchanger or radiator 1840. The heat exchanger radiates the heatoutside of the sealed inductor housing 2010. The process of heat removaltransfer allows the inductor 230 to maintain an about steady statetemperature under load.

For instance, an inductor 230 with an annular core, a doughnut shapedinductor, an inductor with a toroidal core, or a substantially circularshaped inductor is at least partially immersed in an immersion coolant,where the coolant is in intimate and direct thermal contact with amagnet wire, a winding coating, or the windings 610 about a core of theinductor 230. Optionally, the inductor 230 is fully immersed or sunk inthe coolant. For example, an annular shaped inductor is fully immersedin an insulating coolant that is in intimate thermal contact with theheated magnet wire heat of the toroid surface area. Due to the directcontact of the coolant with the magnet wire or a coating on the magnetwire, the coolant is substantially non-conducting.

The immersion coolant comprises any appropriate coolant, such as a gas,liquid, gas/liquid, or suspended solid at any temperature or pressure.For example, the coolant optionally comprises: a non-conducting liquid,a transformer oil, a mineral oil, a colligative agent, a fluorocarbon, achlorocarbon, a fluorochlorocarbon, a deionized water/alcohol mixture,or a mixture of non-conducting liquids. Less preferably, the coolant isde-ionized water. Due to pinholes in the coating on the magnet wire,slow leakage of ions into the de-ionized water results in anelectrically conductive coolant, which would short circuit the system.Hence, if de-ionized water is used as a coolant, then the coating shouldprevent ion transport. Alternatively, the de-ionized cooling water isperiodically filtered and/or changed. Optionally, an oxygen absorber isadded into the coolant, which prevents ozonation of the oxygen due theremoval of the oxygen from the coolant.

Still referring to FIG. 20 , the inductor housing 2010 optionallyencloses two or more inductors 230. The inductors 230 are optionallyvertically mounted using mounting hardware 422 and a clamp bar 234. Theclamp bar optionally runs through the two or more inductors 230. Anoptional clamp bar post 423 is positioned between the inductors 230.

Chill Plate

Often, an inductor 230 in an electrical system is positioned in industryin a sensitive area, such as in an area containing heat sensitiveelectronics or equipment. In an inductor 230 cooling process, heatremoved from the inductor 230 is typically dispersed in the localenvironment, which can disrupt proper function of the sensitiveelectronics or equipment.

In yet still another example, a chill plate is optionally used tominimize heat transfer from the inductor 230 to the local surroundingenvironment, which reduces risk of damage to surrounding electronics.Referring now to FIG. 21 , one or more inductors 230 are placed into aheat transfer medium. Moving outward from an inductor, FIG. 21 isdescribed in terms of layers. In a first layer about the inductor, athermal transfer agent is used, such as an immersion coolant 2020,described supra. Optionally, the heat transfer medium is a solid, asemi-solid, or a potting compound, as described supra. In a second layerabout the immersion coolant, a heat transfer interface 2110 is used. Theheat transfer interface is preferably a solid having an inner wallinterface 2112 and an outer wall interface 2114. In a third layer, achill plate is used. In one case, the chill plate is hollow and/or haspassages to allow flow of a circulating coolant. In another case, thechill plate contains cooling lines 1830 through which a circulatingcoolant flows. An optional fourth layer is an outer housing or air.

In use, the inductor 230 generates heat, which is transferred to theimmersion coolant. The immersion coolant transfers heat to the heattransfer interface 2110 through the inner wall surface 2112.Subsequently, the heat transfer interface 2110 transfers heat throughthe outer wall interface 2114 to the chill plate. Heat is removed fromthe chill plate through the use of the circulating fluid, which removesthe heat to an outside environment removed from the sensitive area inthe local environment about the inductor 230.

Phase Change Cooling

Referring now to FIG. 22 , a phase change inductor cooling system 2200is illustrated. In the phase change inductor cooling system 2200, arefrigerant 2260 is present about the inductor 230, such as in directcontact with an element of the inductor 230, in a first liquidrefrigerant phase 2262 and in a second gas refrigerant phase 2264. Thephase change from a liquid to a gas requires energy or heat input. Heatproduced by the inductor 230 is used to phase change the refrigerant2260 from a liquid phase to a gas phase, which reduces the heat of theenvironment about the inductor 230 and hence cools the inductor 230.

Still referring to FIG. 22 , an example of the phase change inductorcooling system 2200 is provided. An evaporator chamber 2210, whichencloses the inductor 230, is used to allow the compressed refrigerant2260 to evaporate from liquid refrigerant 2262 to gas refrigerant 2264while absorbing heat in the process. The heated and/or gas phaserefrigerant 2260 is removed from the evaporator chamber 2210, such asthrough a refrigeration circulation line 2250 or outlet and isoptionally recirculated in the cooling system 2200. The outletoptionally carries gas, liquid, or a combination of gas and liquid.Subsequently, the refrigerant 2260 is optionally condensed at anopposite side of the cooling cycle in a condenser 2220, which is locatedoutside of the cooled compartment or evaporation chamber 2210. Thecondenser 2220 is used to compress or force the refrigerant gas 2264through a heat exchange coil, which condenses the refrigerant gas 2264into a refrigerant liquid 2262, thus removing the heat previouslyabsorbed from the inductor 230. A fan 240 is optionally used to removethe released heat from the condenser 2220. Optionally, a reservoir 2240is used to contain a reserve of the refrigerant 2240 in therecirculation system. Subsequently, a gas compressor 2230 or pump isoptionally used to move the refrigerant 2260 through the refrigerantcirculation line 2250. The compressor 2230 is a mechanical device thatincreases the pressure of a gas by reducing its volume. Herein, thecompressor 2230 or optionally a pump increases the pressure on a fluidand transports the fluid through the refrigeration circulation line 2250back to the evaporation chamber 2210 through an inlet, where the processrepeats. Preferably the outlet is vertically above the inlet, the inletis into a region containing liquid, and the outlet is in a regioncontaining gas. In one case, the refrigerant 2260 comprises1,1,1,2-Tetrafluoroethane, R-134a, Genetron 134a, Suva 134a or HFC-134a,which is a haloalkane refrigerant with thermodynamic properties similarto dichlorodifluoromethane, R-12. Generally, any non-conductiverefrigerant is optionally used in the phase change inductor coolingsystem 2200. Optionally, the non-conductive refrigerant is an insulatormaterial resistant to flow of electricity or a dielectric materialhaving a high dielectric constant or a resistance greater than 1, 10, or100 Ohms.

Cooling Multiple Inductors

In yet another example, the cooling system optionally simultaneouslycools multiple inductors 230. For instance, a series of two or moreinductor cores of an inductor/converter system are aligned along asingle axis, where a single axis penetrates through a hollow geometriccenter of each core. A cooling line or a potting material optionallyruns through the hollow geometric center.

Cooling System

Preferably cooling elements work in combination where the coolingelements include one or more of:

-   -   a thermal transfer agent;        -   a thermally conductive potting agent;        -   a circulating coolant;    -   a fan;    -   a shroud;    -   vertical inductor mounting hardware 422;    -   a stand holding inductors at two or more heights from a base        plate 210;    -   a cooling line 1830;        -   a wrapping cooling line 1832 about the inductor 230;        -   a concentric cooling line on a face 417 of the inductor 230        -   a pass through cooling line 1834 passing through the            inductor 230    -   a cooling coil;    -   a heat sink 1640;    -   a chill plate 2120; and        -   coolant flowing through the chill plate.

In another embodiment, the winding 620 comprises a wire having anon-circular cross-sectional shape. For example, the winding 620comprises a rectangular, rhombus, parallelogram, or square shape. In onecase, the height or a cross-sectional shape normal or perpendicular tothe length of the wire is more than ten percent larger or smaller thanthe width of the wire, such as more than 15, 20, 25, 30, 35, 40, 50, 75,or 100 the length.

Filtering

The inductor 230 is optionally used as part of a filter to: process oneor more phases and/or is used to process carrier waves and/or harmonicsat frequencies greater than one kiloHertz.

Winding

Referring now to FIG. 23 , the inductor core 610 is wound with thewinding 620 using one or more turns. Optionally, individual windings aregrouped into turn locations, as described supra. As illustrated in FIG.22 , a first turn location 2310 is wound with a first turn of a firstwire, a second turn location 2320 is wound with a second turn of thefirst wire, and a third turn location is wound with a third turn of thefirst wire, where the process is repeated n times, where n is a positiveinteger. Optionally, a second, third, fourth, . . . , a^(th) wires woundwith each of the a^(th) wires are wound with a first, second, third, . .. , b^(th) turn sequentially in the n locations, where the a^(th) wiresare optionally wired electrically in parallel, where a and b arepositive integers. As illustrated in the second turn location 2320, theturns are optionally stacked. As illustrated in the third turn location2330, the turns are optionally stacked in a semi-close packedorientation, where a first layer of turns 2332, a second layer of turns2334, a third layer of turns 2336, and a c^(th) layer of turns compriseincreased radii from a center of the inductor core 610, where c is apositive integer.

Still referring to FIG. 23 and now referring to FIGS. 24 (A-C), theinductor core is optionally of any shape. An annular core is illustratedin FIG. 23 , a 2-phase U-core inductor 2400 is illustrated in FIG. 24A,and a 3-phase E-core inductor 2450 is illustrated in FIG. 24B, whereeach core is wound with a winding using one or more turns as furtherdescribed, infra.

Referring again to FIGS. 24A and 24C, the U-core inductor 2400 isfurther described. The U-core inductor 2400 comprises a core loopcomprising: a first C-element backbone 2410 and a second C-element 2420backbone where ends of the C-elements comprise: a first yoke and asecond yoke. As illustrated, the first yoke comprises a first yoke-firsthalf 2412 and a first yoke-second half 2422 separated by an optional gapfor ease of manufacture. Similarly, the second yoke comprises a secondyoke-first half 2414 and a second yoke-second half 2424 again separatedby an optional gap for ease of manufacture. The first yoke is wound witha first phase winding 2430, shown with missing turns to show the gap,and the second yoke is wound with a second phase winding 2440, againillustrated with missing coils to show the gap. Referring now to FIG.24C, the second phase winding 2440 is illustrated with three layers ofturns, a first layer 2442, a second layer 2444, and a third layer 2446,where any number of layers with any stacking geometry is optionallyused. Individual layers are optionally wired electrically in parallel.

Referring now to FIG. 24B, the E-core inductor 2450 is furtherdescribed. The E-core comprises: a first E-core backbone 2460 and asecond E-core backbone 2462 connected by three yokes, a first E-yoke2464, a second E-yoke 2466, and a third E-yoke 2468. The three yokeseach optionally have gaps for ease of manufacture; however, asillustrated a first E-yoke winding 2472, a second E-yoke winding 2474,and a third E-yoke winding 2476 hide the optional gaps.

Referring again to FIG. 23 and FIGS. 24 (A-C), any of the gaps, turns,windings, winding layers, and/or core materials described herein areoptionally used for any magnet core, such as the annular, “U”, and “E”cores as well as a core for a single phase, such as a straightrod-shaped core.

Core Material

Referring now to FIG. 25 , L-C filtering performance of core materials2500 are described and compared with Bode curves. A circuit, such as aninductor-capacitor or LC circuit, further described infra, generallyfunctions over a frequency range to attenuate carrier, noise, and/orupper frequency harmonics of the carrier frequency by greater than 10,20, 30, 40, 50, 60, 70, 80, 90, 95, 99, or 99.9 percent or greater than20, 30, 40, 50, 60, or 70 decibels. For a traditional solid,non-powdered, iron based core, iron core filter performance 2510, suchas for a 60 Hz/100 ampere signal, is illustrated as a dashed line, wherethe traditional iron core is any iron-steel, steel, laminated steel,ferrite, ferromagnetic, and/or ferromagnetic based substantially solidcore. The curve shows enhanced filter attenuation, from a peak at1/(2π(LC)^(1/2)), at about 600 Hertz down to a minimum, at the minimumresonance frequency, after which point the core material rapidlydegrades due to laminated steel inductor parasitic capacitance.Generally, inductor filter attenuation ability degrades beyond a minimumresonance frequency for a given current, where beyond the minimumresonance frequency a laminated steel and/or silicon steel inductoryields parasitic capacitance. For iron, the minimum resonant frequencyoccurs at about thirty kiloHertz, such as for 60 Hz at 100 amperes,beyond which the iron overheats and/or fails as an inductor. Generally,for ampere levels greater than about 30, 50, or 100 amperes, iron-steelcores fail to effectively attenuate at frequencies greater than about10, 20, or 30 kHz. However, for the distributed gap inductor describedherein, the filter attenuation performance continues to improve, such ascompared to the solid iron core inductor 2532, past one kiloHertz, suchas past 30, 50, 100, or 200 kiloHertz up to about 500 kiloHertz, 1megaHertz (MHz), or 3 MHz even at high ampere levels, such as greaterthan 20, 30, 50, or 100 amperes, as illustrated with the distributed gapfilter performance curve 2520. As such, the distributed gap corematerial in the inductor of an inductor-capacitor circuit continues tofunction as an inductor in frequency ranges 2530 where a solid ironbased inductor core fails to function as an inductor, such as past theabout 10, 20, or 30 kiloHertz. In a first example, for a 30 kHz carrierfrequency, the traditional steel-iron core cannot filter a firstharmonic at 60 kHz or a second harmonic at 90 kHz, whereas thedistributed gap cores described herein can filter the first and secondharmonics at 60 and 90 kHz, respectively. In a second example, thedistributed gap based inductor core can continue to suppress harmonicsfrom about 30 to 1000 kHz, from 50 to 1000 kHz, and/or from 100 to 500kHz. In a third example, use of the distributed gap core material and/ornon-iron-steel material in the an LC filter attenuates 60 dB, for atleast a first three odd harmonics, of the carrier frequency as the firstthree harmonics are still on a filtered left side or lower frequencyside of an inductor resonance point and/or self-resonance point, such asillustrated on a Bode plot. Hence, the distributed gap cores describedherein perform: (1) as inductors at higher frequency than is possiblewith solid iron core inductors and (2) with greater filter attenuationperformance than is possible with iron inductors to enhance efficiency.

Filter Circuit

Referring now to FIG. 26 , a parasitic capacitance removing LC filter2600 is illustrated, which is an LC filter with optional extraelectrical components. The LC filter includes at least the inductor 230and the capacitor 250, described supra. The optional electricalcomponents 2630 function to remove noise and/or to process parasiticcapacitance.

High Frequency LC Filter:

Referring now to FIG. 26 , the high frequency LC filter 145, which is alow-pass filter, is further described. An example of a parasiticcapacitance removing LC filter 2600 is illustrated. However, the onlyrequired elements of the high frequency LC filter 145 are the inductor(L) 230, such as any of the inductors described herein, and thecapacitor (C) 250. Optionally, additional circuit elements are used,such as to filter and/or remove parasitic capacitance. In one example, aparasitic capacitance filter 2630 uses one or more of: (1) a parasiticcapacitance capacitor 2632 wired electrically in parallel with theinductor 230; and/or (2) a set of parasitic capacitance capacitors wiredin series, where the set of capacitors is wired in parallel with theinductor 230. In another example, the optional electrical components ofthe parasitic capacitance removing LC filter include: (1) a parasiticcapacitance inductor and/or a parasitic capacitance resistor wired inseries with the capacitor 250; (2) one or both of a resistor, C_(R),2636 and a second inductor, C_(l), 2634 wired in series with thecapacitor 250; and/or (3) a resistor wired in series with the inductor230, where the resistor wired in series with the inductor 230 areoptionally electrically in parallel with the parasitic capacitancecapacitor 2632 (not illustrated).

Variable Current Operation

Generally, power loss is related to the square of current timeresistance. Hence, current is the dominant term in power loss.Therefore, for efficiency, the operating current of a device ispreferably kept low. For example, instead of turning on a device, suchas an air conditioner operating at a high voltage and current, fully onand off, it is more efficient to replace the on/off relay with a driveto run the device continuously, such as at a lower voltage oftwenty-five volts with a corresponding lower current. However, the driveoutputs a noisy signal, which can hinder the device. A filter, such asan inductor capacitance (LC) filter, is used to filter the highfrequency noise allowing operation of the device at a fixed lowercurrent or a variable lower current. At high currents, traditionallaminated steel inductors in the LC filter loose efficiency and/or fail,whereas distributed gap based inductors still operate efficiently.Differences in filtering abilities of the laminated steelinductor-capacitor and the distributed gap inductor-capacitor arefurther described herein.

LC Filter

Referring now to FIG. 27A, an inductor-capacitor filter is illustrated,which is referred to herein as an LC filter. The LC filter optionallyuses a traditional laminated steel inductor or a distributed gapinductor, as described supra. Generally, an inductor has increasingattenuation as a function a frequency and a capacitor tends to favorhigher frequencies. Hence, an inductor, wired in series, has anincreasing attenuation as a function of frequency and the capacitor,linked closer to ground and acting as a drain, discriminates againsthigher frequencies. For a drive filter system using low current, atraditional laminated steel inductor suffices. However at highercurrents, such as at greater than 50 or 100 amperes, the traditionallaminated steel inductors and/or foil winding inductors fail toefficiently pass the carrier frequency, such as at above 500, 600, 700,800, 900, or 1000 Hz and fail to attenuate the noise above 30, 50, 100,or 200 kHz, as illustrated in FIG. 25 and FIG. 27B. In stark contrast,the distributed gap inductor, described supra, continues to pass thecarrier frequency far beyond 500 or 1000 Hz up to 0.25, 0.5, or 1.0 MHzand reduces higher frequency noise, such as in the range of up to 1-3MHz before parasitic capacitance becomes a concern, as further describedinfra.

High Frequency LC Filter

Referring now to FIG. 27B, LC filter attenuation as a function offrequency 2700 is illustrated for LC filters using traditional laminatedsteel inductors 2710, which are referred to herein as traditional LCfilters. The illustrated filter shapes are offset along the y-axis forclarity of presentation. The traditional laminated steel inductors in anLC circuit efficiently pass low frequencies, such as up to about 500 Hz.However, at higher frequencies, such as at greater than 600, 700, or 800Hz, the traditional LC filters begin to attenuate the signal resultingin an efficiency loss 2722 or falloff from no attenuation. Using atraditional laminated steel inductor, the position of the roll-off inefficiency is controllable to a limited degree using various capacitorand filter combinations as illustrated by a first traditional LC filtercombination 2712, a second traditional LC filter combination 2714, and athird traditional LC filter combination 2716. However, the roll-off inefficiency 2722 occurs at about 800 Hz regardless of the componentparameters in a traditional LC filter 2710 due to the physicalproperties of the steel in the laminated steel. Thus, use of atraditional laminated steel inductor in an LC filter results in lostefficiency at greater than 600 to 800 Hz with still increasing loss inefficiency at still higher frequencies, such as at 1, 1.5, or 2 kHz. Instark contrast, use of a distributed gap core in the inductor in adistributed gap LC filter 2730 efficiently passes higher frequencies,such as greater than 800, 2,000, 10,000, 50,000, or 500,000 Hz.

High Frequency Notched LC Filter

When an LC filter is on or off, efficiency is greatest and when an LCfilter is switching between on and off, efficiency is degraded. Hence,an LC filter is optionally and preferably driven at lower frequencies toenhance overall efficiency. Returning to the example of a fundamentalfrequency of 800 Hz, the distributed gap LC filter 2730 is optionallyused to remove very high frequency noise, such as at greater than 0.5,1, or 2 MHz. However, the distributed gap LC filter 2730 is optionallyused with a second low-pass filter and/or a notch filter to reduce highfrequency noise in a range exceeding 1, 2, 3, 5, or 10 kHz and less than100, 500, or 1000 kHz. The second LC filter, notch filter, and relatedfilters are described infra.

Referring now FIG. 28A, a notched low-pass filter circuit isillustrated. A notched low-pass filter 2800 is also referred to hereinas a first low-pass filter 2270. Generally, the first low-pass filter2810 is coupled with either: (1) the traditional laminated steelinductors 2710 or (2) more preferably the distributed gap LC filter2740, either of which are herein referred to as a second low-pass filter2820. Several examples, infra, illustrate the first low-pass filtercoupled to the second low-pass filter.

Still referring to FIG. 28A, in a first example, the first low-passfilter 2810 comprises a first inductor element, L₁, 2812 connected inseries to a third inductor element, L₃, 2822 of the second low-passfilter 2820 and a second capacitor, C₂, 2814 connected in parallel tothe second low-pass filter 2820, which is referred to herein as an LC-LCfilter. The LC-LC filter yields a sharper cutoff of the combinedlow-pass filter.

Still referring to FIG. 28A, in a second example, the first low-passfilter 2810 comprises: (1) a first inductor element, L₁, 2812 connectedin series to a third inductor element, L₃, 2822 of the second low-passfilter 2820 and (2) a notch filter 2830 comprising a second inductorelement, L₂, 2816, where the first inductor element to second inductorelement (L₁ to L₂) coupling is between 0.3 and 1.0 and preferably about0.9±0.1, where L₂ is wired in series with the first capacitor, C₁, 2814,where the notch filter 2830 is connected in parallel to the secondlow-pass filter 2820. The resulting filter is referred to herein as anyof: (1) an LLC-LC filter, (2) a notched LC filter, (3) the notchedlow-pass filter 2800, and/or (4) a low pass filter combined with a notchfilter and a high frequency roll off filter. In use, generally thesecond inductor element, L₂, 2816 and the first capacitor, C₁, 2814combine to attenuate a range or notch of frequencies, where the range ofattenuated frequencies is optionally configured using differentparameters for the second inductor element, L₂, 2822 and the firstcapacitor, C₁, 2814 to attenuate fundamental and/or harmonic frequenciesin the range of 1, 2, 3, 5, or 10 kHz to 20, 50, 100, 500, or 1000 kHz.The effect of the notch filter 2830 is a notched shape or attenuatedprofile 2722 in the base distributed gap based LC filter shape.

Referring now to FIG. 28B, filtering efficiencies 2850 are compared fora traditional laminated steel based LC filter 2860, a distributed gapbased LC filter 2870, and the notched low-pass filter 2800. Asdescribed, supra, the traditional laminated steel based LC filter 2860attenuates some carrier frequency signal at 800 Hz, which reducesefficiency of the LC filter. Also, as described supra, while thedistributed gap based LC filter 2870 efficiently passes the carrierfrequency at 800 Hz, efficient attenuation of the fundamental frequencyoccurs at relatively high frequencies, such as at greater than 500 kHz.However, the notched low-pass filter 2800 both: (1) efficiently passesthe carrier frequency at 800 Hz and (2) via the notch filter 2830attenuates the fundamental frequency at a low frequency, such as at 2kHz±0.5 to 1 kHz, where the lower switching frequency enhancesefficiency of the filter.

Still referring to FIG. 28B, the notch 2802 of the notched low-passfilter 2800 is controllable in terms of: (1) frequency of maximum notchattenuation 2808, (2) roll-off shape/slope of the short-pass filter2512, and (3) degree of attenuation through selection of the parametersof the second inductor element, L₂, 2816 and/or the first capacitor, C₁,2814 and optionally with a resistor in series with the second inductor2816 and first capacitor 2814, where the resistor is used to broaden thenotch. One illustrative example is a second notched low-pass filter2804, which illustrates an altered roll-off shape 2806, notch minimum2808, and recovery slope 2809 of the notch filter relative to the firstnotched low-pass filter 2800.

Still referring to FIG. 28B, via selection of parameters of at least oneof the second inductor element, L₂, 2816 and/or the first capacitor, C₁,2814 in view of selection of at parameters for other elements of thenotched low-pass filter 2800, the overall notched low-pass filter shaperesults in any of:

-   -   less than 2 or 5 dB attenuation of the carrier frequency at 500,        600, 700, 800, 900, or 1,000 Hz;    -   greater than 20, 40, 60, or 80 dB of attenuation at 1, 2, 3, 4,        or 5 kHz;    -   a ratio of a carrier frequency attenuated less than 10 dB to an        attenuation frequency attenuated at greater than 60 dB of less        than 800 to 2000, 8:20, 1:2, 1:3, 1:4, or 1:5;    -   a width of 50% of maximum attenuation of the notch filter of        less than 1, 2, 3, 4, 5, 10, 50, or 100 kHz;    -   a width of 50% of maximum attenuation of the notch filter of        greater than 1, 2, 3, 4, 5, 10, 50, or 100 kHz;    -   a maximum notch filter attenuation within 1 kHz of 1, 2, 3, 4,        5, 7, and 10 kHz; and/or    -   a maximum notch filter attenuation at greater than any of 1, 2,        3, 5, 10, 20, and 50 kHz and less than any of 3, 5, 10, 20, 50,        100, 500, or 1,000 kHz.

To further clarify the invention and without loss of generality, exampleparameters for the first low-pass filter 2810 are provided in Table 3.

TABLE 3 Notch Filter Notch Filter L₁ L₂ C₁ R₁ Purpose (μH) (μH) (μF)(Ohm) best filter 10 ± 5 4 ± 3 300 ± 50 2 ± 2

To further clarify the invention and without loss of generality, exampleparameters for the notched low-pass filter 2800 are provided in Table 4.

TABLE 4 Notched Low-Pass Filter First Low-Pass Second Low-Pass FilterFilter L₁ L₂ C₁ R₁ L₃ C₂ Purpose (μH) (μH) (μF) (Ohm) (μH) (μF) 800 Hzcarrier; 12 ± 5 3 ± 2 300 ± 50 3 ± 2 30 ± 20 200 ± 100 2000 Hz notch

Modular Inductor/Winding

Referring now to FIG. 29A through FIG. 35 , a modular winding systemand/or a modular inductor system is described. Optionally andpreferably, the modular inductor system includes flat windings and/orbalanced and opposing magnetic fields in an equal coupling common modeinductor apparatus.

Flat Winding

Referring now to FIG. 29A and FIGS. 30 (A-C), an optional flat windingsystem 3000 of the modular inductor system is described.

Referring still to FIG. 29A, a flat winding coil 2900 is described. Theflat winding coil 2900 is used in place of a traditional round copperwinding about an inductor core and/or in conjunction with a traditionalcopper wire winding. For clarity of presentation and without loss ofgenerality, the flat winding coil 2900 is illustrated as alongitudinally elongated conductor, such as comprising a rectangularcross-section. More generally, the flat winding coil comprises anythree-dimensional geometry, such as further described infra.

Referring again to FIG. 30A and FIG. 30B, the flat winding coil 2900 isillustrated in a wound configuration about the inductor core 610. Thewound coil configuration comprises an inner radius of curvature ofgreater than 0.4 inches and less than twenty inches, such as about 1,1.5, 2, 3, 4, 5, or 10 inches. A cross-sectional width of the flatwinding coil 2900 is greater than a cross-sectional height of the flatwinding coil. For example, the width of the flat winding coils isgreater than or equal to 0.5, 0.75, 1, 1.25, 1.5, 2, or 3 inches and theheight of the flat winding coil is less than or equal to 0.75, 0.5,0.25, 0.125 or 0.0625 inches. The flat aspect of the flat winding coil2900 allows for more rapid and efficient transfer of heat, conduction,versus a traditional round wire inductor winding as a result ofincreased surface area per unit volume. Generally, a winding coil has afirst connector 2902 and a second connector 2904.

Example I

For example, referring now to FIG. 29B, a circular cross-section of atraditional round wire with a radius of 1.000 has a cross-section areaof πr² or 3.14 and has a perimeter of 2πr or 6.28. Referring now to FIG.29C, a first rectangular wire, with the same cross-section area of 3.14has a width and height of 3.0 and 1.047, respectively, but has anincreased perimeter of 2(l+w) or 8.09, which is an increase of 29%versus the round wire. Similarly, referring now to FIG. 29D, a secondrectangular wire, with the same cross-section area of 3.14 has a widthand height 6 and 0.524, respectively, but has an increased perimeter of2(l+w) or 13.05, which is an increase of 108% versus the round wire.

The inventor notes that the greater the width-to-height ratio, thegreater the percent increase in surface area of the winding, where theincreased surface area results in more rapid cooling of the winding asthere is more area in contact with the cooler surrounding, such as airor a liquid coolant. Thus, a preferred width-to-height ratio of thewinding is greater than or equal to 1.2, 1.5, 2, 2.5, 3, 5, or 10.

Referring again to FIG. 30A and FIG. 30B, convection cooling of the flatwinding system is described. As illustrated, an airflow, optionally aliquid flow, passes between individual turns of the flat winding coil2900, which enhances cooling of the flat winding coil 2900 and theinductor core 610. The inventor notes that the increased surface area ofthe flat winding coil increases effectiveness of the convection coolingcompared to use of a traditional round cross-section wire winding.Further, the above described conduction operates synergistically withthe convection process.

Referring now to FIG. 30C, a system of multiple flat windings 3010 isdescribed. As illustrated, a first flat winding coil 3012 is wrapped,such as with multiple turns, about the inductor core. A separate secondflat winding coil 3014 is wrapped, preferably with multiple turns, aboutthe first flat winding coil 3012. A third flat winding coil 3016 isoptionally and preferably circumferentially wrapped: (1) around thefirst flat winding coil 3012 and (2) in contact with and around thesecond flat winding coil 3014. Generally, n levels of windings are woundaround the inductor core 610, where n is a positive integer of at least1, 2, 3, 4, 5, 6, 10, or 15. Optionally and preferably, the n windingwires are wired in parallel, as described supra.

Balanced Magnetic Fields

Referring now to FIG. 31 through FIG. 35 , a balanced magnetic fieldfilter system 3100 is described. Referring still to FIG. 31 , ingeneral, 3-phase voltage 3110/power is processed, such as by using aninductor-capacitor filter 3120. Optionally and preferably, theinductor-capacitor filter 3120 uses opposing magnetic fields 3122in/about the inductors, as further described infra. Still further, theopposing magnetic fields 3122 optionally and preferably yield a balancedmagnetic field 3124, as further described infra. Still further, theopposing and balanced magnetic fields are optionally and preferablygenerated passively with a mechanical system in the absence of movingparts and/or computer control, as further described infra. Any of thebalanced magnetic field systems optionally use the flat winding coil2900 and/or the flat winding system 3000, described supra.

Referring now to FIG. 32A, a 3-phase balanced magnetic field processingsystem 3200 is illustrated, such as for use in filtering a three-phasepower supply system, where each line of the three phases carries analternating current of the same frequency and voltage amplitude relativeto a common reference but with a phase difference of one third theperiod and/or 120 degrees.

For clarity of presentation and without loss of generality, thethree-phase processed current and voltage is referred to herein as athree-phase system. Herein, referring again to FIG. 2 , the three-phasesystem is denoted with a first line, U; a second line, V; and a thirdline W.

Referring again to FIG. 32A, as illustrated, the first phase, U, isprocessed using a first inductor 3210, the second phase, V, is processedusing a second inductor 3220, and the third phase, W, is processed usinga third inductor 3230. Current passing along the winding in each phasegenerates a magnetic field. Particularly, a first current, from thefirst phase, passing through a first winding of the first inductor 3210generates a first magnetic field, B₁. Similarly, a second current, fromthe second phase, passing through a second winding of the secondinductor 3220 generates a second magnetic field, B₂, and a thirdcurrent, from the third phase, passing through a third winding of thethird inductor 3230 generates a third magnetic field, B₃. For clarity ofpresentation, the second winding of the second inductor 3220 and thethird winding of the third inductor 3230 are not illustrated to allow aview of the optional modular cores, described infra.

Referring still to FIG. 32A and now to FIG. 32B, the first, second, andthird magnetic fields, B₁, B₂, B₃ generated by the first phase, U, thesecond phase, V, and the third phase, W, are respectively illustrated inthe first inductor 3210, the second inductor 3220, and the thirdinductor 3230. Generally, the sum of the three magnetic fields B₁, B₂,B₃, is a constant, such as zero, as in equation 1.B ₁ +B ₂ +B ₃=0  (eq. 1)

Generally the symmetrical 3-phase balanced magnetic field processingsystem 3200 balances the magnetic field of each inductor, of the threeinductors, using the magnetic fields of the remaining two inductors ofthe three inductors, which results in a balanced magnetic system whichdoes not create common mode noise. In stark contrast, unbalancedthree-phase magnetic systems are sources that generate common modenoise, as further described infra.

Example 1

An example is provided to further describe the balanced magnetic fieldsof the symmetrical layout of the 3-phase balanced magnetic fieldprocessing system 3200. Referring still to FIG. 32A and FIG. 32B, the3-phase system is further described where amplitude of thecurrent/voltage is related to the magnetic field of the respectiveinductor. For instance, as illustrated at a first time, t₁, the relativeamplitude of the first magnetic field, B₁, is 1.0 while the amplitude ofthe second magnetic field, B₂, is −0.5 and the amplitude of the thirdmagnetic field, B₂, is −0.5, where the sum of the three magnetic fieldsis zero, as in equation 1. At this first time, three magnetic fieldloops are further described.

Still referring to FIG. 32A, a first magnetic field loop, B₁B₂, and athird magnetic field loop, B₁B₃, are described where the magnetic fieldlines and directions are illustrated at the first time, t₁. The firstmagnetic field loop, B₁B₂, sequentially passes/cycles up through thefirst inductor 3210, along/through a first upper plate section 3252,along/through a second upper plate section 3254, down through the secondinductor 3220, along/though a second lower plate section 3264,along/through a first lower plate section 3262, and back up through thefirst inductor 3210. Similarly, the third magnetic field loop, B₁B₃,sequentially passes/cycles up through the first inductor 3210,along/through the first upper plate section 3252, along/through a thirdupper plate section 3256, down through the third inductor 3230,along/though a third lower plate section 3266, along/through the firstlower plate section 3262, and back up through the first inductor 3210.

In the illustrated 3-phase balanced magnetic field processing system3200, the first magnetic field, B₁, of +1.0 in the first inductor 3210is split at the centrally positioned end of the first upper platesection 3252 along the second upper plate section 3254 and the thirdupper plate section 3256, where ‘+’ demarks a magnetic field in a firstdirection and ‘−’ demarks a magnetic field in the opposite direction.Thus, still at the first time, t₁, the first inductor 3210 and the firstmagnetic field, B₁, of +1.0 results in: (1) a field of +0.5 applied tothe second inductor 3220 balancing the −0.5 field in the second inductor3220 at the first time, t₁, and (2) a field of +0.5 applied to the thirdinductor 3230, which balances the −0.5 field in the third inductor 3230at the first time, t₁.

At subsequent times, such as a second time, t₂, and a third time, t₃,the magnitude and direction of each the three magnetic fieldssinusoidally vary, but the sum of the magnetic fields in each of thethree inductors, 3210, 3220, 3230, continues to add to zero as a resultof the geometry of the 3-phase balanced magnetic field processing system3200, as further described, infra.

3-Phase Inductor Geometry

Referring still to FIG. 32A and referring now to FIG. 32C, geometry ofthe 3-phase balanced magnetic field processing system 3200 is furtherdescribed. The three inductors 3210, 3220, 3230 have a common upperplate 3250 comprising the first upper plate section 3252, the secondupper plate section 3254, and the third upper plate section 3256.Similarly, the three inductors 3210, 3220, 3230 have a common lowerplate 3260 comprising the first lower plate section 3262, the secondlower plate section 3264, and the third lower plate section 3266.Optionally and preferably the material, size, and shape of the threesections of the upper plate 3250 and/or the three sections of the lowerplate 3260 are the same to yield a balanced magnetic field conduit path.Further, as illustrated each of, a first angle alpha, α, a second anglebeta, β, and a third angle delta, δ, are equal and 120 degrees. Inpractice, magnetic field resistance and/or permeability of the upperplate sections 3250 and/or the lower plate sections 3260 are within 1,2, 3, 5, or 10 percent of each other and/or the first, second, and thirdangles are optionally 110 to 130 degrees, such as about 118, 119, 121,and/or 122 degrees.

As illustrated, with the first, second, and third angles at 120 degrees,each of: (1) a first distance between the first inductor 3210 and thesecond inductor 3220, B, to B₂, (2) a second distance between the secondinductor 3220 and the third inductor 3220, B₂ to B₃, and (3) a thirddistance between the first inductor 3210 and the third inductor 3230, B,to B₃, are equal. Equal distances between each combination of the firstinductor 3210, second inductor 3220, and the third inductor 3230 coupledwith common element shapes and/or materials along the upper and lowerplates sections 3250, 3260 results in balanced magnetic fields in eachof the three inductors 3210, 3220, 3230 at times/phases of an input3-phase power supply system, such as the three-phase power grid systemof the United States.

Referring now to FIG. 32D, FIG. 33 , and FIG. 34 , the equal distancebetween the three inductors of the 3-phase balanced magnetic fieldprocessing system 3200 is contrasted with unbalanced systems.Particularly, referring now to FIG. 32D, the 3-phase balanced magneticfield processing system 3200, as described above, includes: (1) equaldistances between the inductors, B₁ to B₂, B₁ to B₃, and B₂ to B₃, and(2) equal magnetic field mediums 3270, such as along paths between theinductors in the upper and lower plate sections 3250, 3260.

Referring now to FIG. 33 , however, when: (1) distances between thedistance between inductors, B₁ to B₂, B₁ to B₃, and B₂ to B₃, areunequal and/or (2) magnetic field mediums 3270, such as along pathsbetween the inductors in the upper and lower plate sections 3250, 3260are unequal and/or are of different length, the magnetic fields in eachof the first inductor 3210, the second inductor 3220, and the thirdinductor 3230 do not balance due to impacts from the other inductors asa function of time. For instance, the first magnetic field of the firstinductor 3210 is not balanced by the magnetic fields from thecombination of the second inductor 3220 and the third inductor 3230 as afunction of time, which yields common mode noise. Referring now to FIG.34 , as the distances between pairs of the three inductors increases,the common mode noise increases. For example, when the three inductorsare on a line, such as in FIG. 34 , the distance between the firstinductor 3210 and the second inductor 3220 is fifty percent or more lessthan a second distance between the first inductor 3210 and the thirdinductor 3230, which results in an unbalanced magnetic system in whichthe summation of the magnetic fields does not equal zero. Since thesummation of the magnetic fields does not equal zero, the unbalancedmagnetic system is generating common mode noise when processing 3-phaseinput voltage systems.

Additional Post Systems

The inventor notes that the 3-phase balanced magnetic field processingsystem 3200 optionally uses one or more additional posts referred toherein as yokes. Referring now to FIG. 35 , an optional first yoke 3240or fourth post, is illustrated. Generally, one or more yokes function tomaintain balanced magnetic fields in the first inductor 3210, the secondinductor 3220, and the third inductor 3230, but more than three totalposts are used, where the term post includes the longitudinalaxis/height or each inductor. Again, the magnetic field paths for thefirst time, t₁, as provided in FIG. 32B, are illustrated. Particularly,at the first time, t₁, the first magnetic field, B₁, when reaching theinner end of the first upper plate section 3252, instead of dividingbetween the second upper plate section 3254 and third upper platesection 3256, a first portion, B_(p), of the first magnetic field passesdown through the first yoke 3240. At the same time, the second magneticfield, B₂, passes down through the second inductor 3220 and up the firstyoke 3240 and the third magnetic field, B₃, passes down through thesecond inductor 3230 and up the first yoke 3240. In this case, themagnetic fields are balanced in the middle 3272 of the first yoke 3240,such as +B_(j)+B₂+B₃=0 or 1.0−0.5−0.5=0. In this case, as the 3-phasebalanced magnetic field processing system 3200 is symmetrical, has C₃rotational symmetry, the magnetic fields are still balanced within eachinductor as a function of time. For instance, any portion of the firstmagnetic field, B₁, passing through the second inductor 3220 and thethird inductor 3230 subtracts from the magnetic field passing downthrough the first yoke 3240, which considering all fields, stillbalances the magnetic field in each of the three inductors 3210, 3220,3230.

Placing additional return yokes in the 3-phase balanced magnetic fieldprocessing system 3200 is optionally done while maintaining balancemagnetic fields, such as by adding a multiple of three yokes, with C₃rotational symmetry, to the three post or four post systems describedsupra.

Cast Inductor

Optionally, one or more elements of the inductor 230 are cast. Forexample, the windings 620 are optionally cast. Herein, a cast part, suchas formed by casting refers to a part manufactured by pouring a liquidmetal, or electrically conducting material, into a mold and aftercooling/curing removing the cast item from the mold. One preferred metalis aluminum and/or an alloy containing at least 50, 60, 70, 80, 90, 95,or 99% aluminum. The solidified part, which is also referred to as acasting, is ejected/broken out of the mold for later use, such as afterremoving runners and risers and/or rough edges. FIGS. 36 (A-C), FIG. 37(A-C), FIG. 38 , and FIG. 39A and FIG. 39B are used to further describecasted windings used with the inductor core 610.

Referring now to FIGS. 36 (A-C) and FIGS. 37 (A-C), wire windings arecompared with flat windings. Referring now to FIG. 36A and FIG. 37A, thefirst wire turn 1141 is compared with a first flat turn 3741. The firstflat turn 3741, optionally and preferably formed by casting, differsfrom the first wire turn 1141 in several ways. In a first example, thefirst flat turn 3741 replaces n wire turns as the cross-sectional areais larger. For instance, 2, 3, 4, 5, 6 or more wire turns are replacedwith a single flat turn. Replacing multiple wire turns with a singleturn reduces manufacturing cost while maintaining electrical fluxcapacity. In a second example, the width of the flat turn, such thefront winding face 3751, increases with radial distance from the centerof the toroid/inductor core 610, whereas the wire turn has a constantwidth with radial distance. In a third example, the cross-sectional areaof the flat turn optionally differs with position, such as by greaterthan 5, 10, or 15 percent, whereas the wire turn has a constantcross-sectional area. The increased cross-sectional area aids in heattransfer, such as a thicker and/or wider section of the winding alongthe face or outer perimeter of the inductor core facilitates heatdissipation to a cooling system and/or the atmosphere. Optionally, heatsinks, such as pillars, are included in the casting to facilitate heattransfer from the faces and/or outer perimeter inductor interfacingareas of the case inductor. In a fourth example, the flat turn isoptionally thicker, such as within the opening of the inductor core 610,and thinner, such as along the faces and/or outer perimeter of theinductor core 610. A thicker section within the aperture of the inductorcore 610 enhances current carrying capacity by using a large fraction ofthe volume of the aperture than winding with coatings allows. Generally,the cast turn is formed via a casting process and the wire turn isformed through a labor intensive winding process as each wire must bethreaded through the aperture of the inductor core 610.

Referring now to FIGS. 36 (A-C) and FIGS. 37 (A-C), wire windings arefurther compared with flat windings. As illustrated in FIGS. 36 (A-C),during manufacturing, the first wire turn 1141 is wound at a first time,t₁; the second wire turn 1142 is wound at a second time, t₂; and thethird wire turn 1143 is wound at a third time, t₃. In stark contrast,during manufacturing, the first flat turn 3741, the second flat turn3742, and the third flat turn 3743 are all cast at one time. Hence, themanufacturing process is further improved by forming many/all of theturns at one time.

Cabinet

Referring now to FIG. 38 , a cabinet 3800, such as a single cabinet, isused to house multiple elements of the power processing system 100. Forinstance, it is beneficial to house multiple elements of the powerprocessing system together to save in manufacturing cost, shipping,storage, and/or installation space. Further, housing multiple elementstogether aid in temperature control, cooling, electrical isolation,and/or safety. Optionally, the cabinet 3810 houses one or more of:

-   -   any inductor described herein;    -   an LC filter;    -   an LCL filter 3820;    -   an active front end (AFE) 3830;    -   a variable frequency drive (VFD) 3840;    -   a sine wave filter (SWF) 3850;    -   an inverter; and/or    -   a converter.

A heat exchange system 3860, such as the radiator 1840/radiator system,is optionally used to cool elements in the cabinet. Elements in thecabinet are optionally connected to the motor 156. Optionally andpreferably, the power processing system 100 processes three-phase power.Optionally and preferably, the LCL filter, variable frequency drive3840, and sine wave filter 3850 are all housed in the cabinet 3800 andare cooled using a liquid cooled cooling system.

Referring now to FIG. 39A, the shape of the flat windings is furtherdescribed. The first flat winding is illustrated with an increasingwidth with radial distance from the center of the inductor core 610. Theincreasing width with radial distance increases surface area for coolingfor a fixed/given amount of metal in the winding, such as aluminum. Thesecond flat winding 3742 is illustrated with a rotational offset 3810 orbend along the face(s) of the inductor core 610, which facilitates thetotal coverage of the inductor core 610 by the inductor windings 620, asfurther described, infra.

Referring now to FIG. 39B and FIG. 39C, the first flat winding 3741 withthe rotational offset 3910 is illustrated in close proximity, closepacked, with the second flat winding 3742. The close packing of the flatwindings, with the rotational offset: increases the mass of the inductorwindings 620 to increase flux of the current passing around sections ofthe inductor core 610 and covers more of the inductor core 610 tofacilitate thermal heat transfer from the inductor core 610 to thesurrounding environment.

Referring now to FIG. 40 , a cast winding assembly element is described.Generally, the cast winding assembly element or cast winding 4000 is anexample of inductor windings 620. However, the cast winding 4000 is castas an element and the inductor core 610 is then inserted into the castwinding 4000 as opposed to the winding being wound turn-by-turn aroundthe inductor core 610. As illustrated, the cast winding 4000 has a firstelectrical connector 2902 and a second electrical connector 2904, a setof flat turns 3740, and a cavity 4010 into which the inductor core isinserted. The cast winding 4000 is optionally and preferably cast out ofaluminum or an aluminum alloy. The cast winding 4000, or a subsectionthereof, is optionally coated and/or plated with another metal, such ascopper, silver, or gold. The cast winding 4000 is optionally andpreferably an arced helical coil, arced helix, bendable helix, and/or aflexible helix, which form the central cavity 4010 into which a doughnutshaped inductor is inserted. When the cast winding 4000 has a pluralityof flat turns, such as n turns, where n is a positive integer greaterthan 5, 6, 7, 8, 9, 10, 15, 20, 25, or 30, the cast winding 4000, thecast winding 4000 is flexible, like an uncompressed slinky, and isreadily twisted to allow insertion of sections of the inductor core 610,described infra.

Referring now to FIG. 41 , an optional manufacturing process 4100 of theinductor 230 is described. In a first process, the winding is cast 4110,such as described supra. In a second process, the cast winding 4000 isdeformed 4120, such as by turning or rotating one or more flat windingturns relative to additional flat winding turns of the set of flat turns3740 and/or by rotating one or more flat winding turns, such as thefirst flat winding 3741 and second flat winding 3742 relative to acentral curved axis running through the cavity 4010. As illustrated inFIG. 40 , the cavity accepts a toroidal inductor core. In a thirdprocess, the inductor core 610 is inserted 4130 into the cavity 4010. Aprocess of inserting the inductor core 610 into the cast winding 4000 isfurther described, infra.

Referring now to FIG. 42 and FIGS. 43 (A-C), an assembly process 4200 ofinserting the core 4130 into the set of flat turns 3740 is described.Generally, the inductor core 610 is provided in two or more sections,such as a first core section 612 and a second core section 614, thatcombine to form the inductor core 610. For example, the sections of theinductor core 610 include 2, 3, 4, or more sub-sections that whencombined form the inductor core 610, such as a first sub-section formingone-half of the inductor core 610 and a second sub-section forming asecond half of the inductor core 610, such as illustrated in FIG. 43A.For instance, in the step of inserting core sections 4210, the firstcore section 612 is inserted into the cavity 4010 and then the secondcore section is inserted into the cavity and the core sub-sections aremechanically linked 4220 and/or are mechanically connected.

Referring now to FIG. 43B, optionally the two or more core sub-sections,such as the first core sub-section 612 and the second core sub-section614, fit together in a lock and key format. As illustrated, a keysection 624 of the second core sub-section 614 inserts into a locksection 622 of the first core sub-section 612. The lock and keyinterface is optionally of any geometry; however, optionally andpreferably the lock and key element combine to form a fully contactinginterface between two or more sub-sections to form a complete inductorcore 610, such as a distributed gap inductor core.

Referring still to FIG. 43B and referring now to FIG. 43C, optionallythe core sub-sections click together via use of an insertion element 644into an insertion gap 642, which is optionally and preferably combinedwith the lock and key format. A positive response function, such as aclick, informs the assembler that a connection between sub-sections isachieved.

Cooling

Referring now to FIG. 44A, FIG. 44B, FIG. 45A, FIG. 45B, and FIG. 46 , acooling system of the inductor 230 using the cast winding 4000 isdescribed, where the cast winding 4000 includes a cast protrusion 626separating casting gaps 628. Referring to FIG. 44A, the optional castprotrusions 626 of the winding 620 is referring to herein as a clamshellsurface of the winding 620. The clamshell surface is further described,infra.

Referring still to FIG. 44A, an example of the winding 620 comprising aflat winding body 625 is illustrated, where a flat/curved/arced surfaceof the winding body 625 is wound around and in contact/proximate contactwith the core 610. The winding body 625, such as in the first flat turn3741, optionally contains a non-planar surface, such as containing oneor more of the cast protrusions 626 that separate the casting gaps 628.The casting gaps protrude from the inductor turn, such as along a z-axisaway from an inductor core, such as far enough to encompass 1, 2, 3, ormore cooling tubes and optionally more than one-fifth, one-fourth,one-third, one-half, or three-quarters of a diameter of a correspondingcooling tube. Optionally, the cast protrusions 626 function as heat sinkfins, such as to dissipate heat to the surrounding atmosphere and/or toa liquid coolant flowing across/around the cast protrusions 626.

Still referring to FIG. 44A and referring now to FIG. 44B, one or moreoptional cooling lines/cooling tubes 4410 are positioned substantiallyinto the casting gaps 628, where a cooling fluid running through thecooling tubes is used to remove heat/energy from the inductor 230.Generally, as least one cooling tube of the set of cooling tubes 4410 ispositioned in at least one casting gap of the set of casting gaps 628.The cooling tube preferably contacts the cast protrusions 626 to aid inthermal transfer. Optionally, the cooling tube is thermally connected tothe cast protrusions, such as via use of a thermal grease. Generally,the cooling tube is less than 0.5, 1, 2, 3, or 5 millimeters from thecast protrusions 626 and/or the winding body 625. The winding body 625and the winding protrusions 626 are optionally and preferably cast, asdescribed supra, such as in the cast winding 4000 and/or such as in thefirst flat turn 3741.

Referring now to FIG. 45A and FIG. 45B, a set of cooling tubes 4510coupled to the inductor 230 is illustrated. Referring now to FIG. 45A,as illustrated, a first cooling tube 4512 and a second cooling tube4514, illustrative of n cooling tubes, are coupled, such as incorresponding casting gaps 628 between corresponding casting protrusions626, to the first flat turn 3741 wrapped about the inductor core 610,where n is a positive integer, such as greater than 0, 1, 2, 3, 4, 5,10, or 20. As illustrated, the cooling tubes run along a first surface,such as the front face 418, of the inductor 230. Referring now to FIG.45B, the cast protrusions 626, the casting gaps 628, and/or the coolingtubes 4410 are illustrated running along multiple surfaces of theinductor 230, such as the inner surface 414 surrounding the centeraperture 412, the front face 418, the outer edge 416, and/or the backface 419 of the inductor 230. As illustrated, the cooling tubes extendradially outward from the center aperture 412, but optionally extendalong any surface of the inductor 230 in any direction.

Referring now to FIG. 46 , an optional cooling jacket system 4600 isdescribed. The cooling jacket 4600 is optionally a clamshell design,where two sections enclose a central object, such as the inductor 230.Generally, the cooling jacket system 4600 includes a cooling jacket 4610comprising at least two sections, which are optionally mechanicallyconnected via a hinge. For example, the cooling jacket 4610 comprises atleast two parts, such as a plurality of coolant containment parts or atop section 4612 of the cooling jacket 4610 and a bottom section 4614 ofthe cooling jacket 4610. The multiple parts come together to surround orcircumferentially surround the wound core/inductor 230 during use. Thetop and bottom halves join each other along any axis of a plane crossingthe inductor 230. Further, the top and bottom sections 4612, 4614 of thecooling jacket 4610 are optionally equal in size or either piece couldbe from 1 to 99 percent of the mass of the sandwiched pair of pieces.For instance, the bottom piece may make up about 10, 25, 50, 75, or 90percent of the combined cooling jacket assembly. Still further, thecooling jacket 4610 may be composed of multiple pieces, such as 3, 4, ormore pieces, where the center pieces are rings sandwiched by the top andbottom sections, or any outer sections, of the cooling jacket.Generally, any number of cooling pieces optionally come together alongany combination of axes to form a jacket cooling the wound core. Eachsection of the cooling jacket optionally contains its own cooling in andcooling out lines and/or a cooling line runs between jacket sections. Asillustrated, a first cooling line 4620 has a first coolant input line4622 connected to a first coolant exit line 2624 via a first internalfluid guide directing the, optionally circulating, coolant over a firstsection of the inductor 230 and a second cooling line 4630 has a secondcoolant input line 4632 connected to a second coolant exit line 2634 viaa second internal fluid guide directing the coolant over a secondsection of the inductor 230. Generally, a given internal fluid guidedirects the coolant along any path, such as forward along a first arc ofthe inductor 230 and in a return path along a second arc of the inductor230.

Flat Winding Shape

Referring now to FIGS. 47 (A-C), optional cast geometries of the set offlat turns 3740 is described. Referring now to FIG. 47A, the first flatturn 3741 of the set of flat turns 3740 is illustrated with an optionalgeometry. For clarity of presentation, the optional geometry isillustrated in four sections, a first volume, v₁, along the innersurface 414; a second volume, v₂, along the front face 418; a thirdvolume, v₃, along the outer edge 416; and a non-visual fourth volume,v₄, along the back face 419 of the inductor 230. Generally, a currentflux capacity is related to a cross-section area of the turn as afunction of longitudinal position along the turn. As the width of thefirst flat turn 3741, as illustrated, increases with radial distancefrom the center 412 of the aperture of the inductor 230, the thicknessof the first flat turn 3741 is optionally made thinner, such as alongthe front face 418 of the inductor 230, as a function of radial distancefrom the center 230 while still maintaining a constant cross-sectionarea of the first flat turn 3741 as a function of radial distance.Similarly, as the first flat turn 3741 has a smaller width along theinner surface 414 of the inductor 230 compared to a larger width alongthe outer edge 416 of the inductor 230, a thicker section of the firstflat turn 3741 along the inner surface 414 and a thinner section of thefirst flat turn along the outer edge 416 yield a constant cross-sectionof the first flat turn 3741 as a function of position around theinductor core 610.

Referring now to FIG. 47B, an optional thickness profile of the firstflat turn 3741 is illustrated, where the thickness of the first volume,along an axis from the center 412 radially outward through a center of asection of the inductor core 610, is thicker than the third volume alongthe same axis and the thickness of the second volume, along an axisperpendicular to the front face 418 of the inductor core 610, decreaseswith radial position. It is thus readily calculated using simplegeometry thicknesses of the first flat turn as a function of positionalong/around the first flat turn 3741 that combined with the varyingwidth of the first flat turn 3741 maintain a constant cross-section areaas a function of position along/around the first flat turn 3741. Thedecreased thickness of the first flat turn as a function of radialdistance from the center 412 along the front face 418 and the back face419 of the inductor 230 reduces required mass, such as requiredaluminum, of the first flat turn 3741 and thus reduces cost whilemaintaining a current flux capacity around the turn. Optionally, thethickness of the first volume, along the axis from the center 412through a center of a section of the inductor core is at least 1, 2, 5,10, 15, 20, 30, 40, 50, or 100 percent greater than the thickness of thethird volume along the same axis. Optionally, the thickness of thesecond volume as a function of radial distance from the center decreasesfrom a first inward radial distance to a second outward radial distanceby at least 1, 2, 5, 10, 20, or 30 percent.

Referring now to FIG. 47C, the first flat winding and a second throughan eighth flat winding, 3742-3748, illustrate that a majority of avolume of the center aperture of the inductor 230 is filled by the setof flat turns 3740. Generally, current carrying sections the set of flatturns 3740 occupy at least 50, 60, 70, 80, or 90 percent of the volumeof the center aperture of the inductor 230, where volume of the currentcarrying metal of traditional wire windings occupy less than 10, 20, 30,or 40 percent of the volume of the center aperture of the inductor dueto the volume requirements of the wire coating about each wire core andmechanical gaps between individual turns, especially for roundcross-section wires which have air gaps between turns and layers ofwindings.

Referring now to FIG. 47D and FIG. 47E, an example of heat sinks 1640optionally cast as a part of the winding are illustrated. For example,the first flat winding 4710 is cast with heat sinks protruding from thesurface of the winding, such as from the front face 418. Air flow and/orcoolant flowing over the heat sinks 1640 removes heat from the inductor230, which aids in longevity of the inductor 230 and efficiency of theinductor 230. Generally, the heat sinks 1640 are of any geometry.Referring now to FIG. 47E, heat sinks are illustrated as protruding fromthe heat sink where the heat sink thickness varies as a function ofposition along the length and/or width of a given turn of the winding.

Harmonic Filter Contactor Controller

Referring now to FIG. 48 , a harmonic filter control system 4800 isdescribed. Generally, a harmonic filter 5000 takes output from anelectrical power source 10, such as the grid 110 or a generator 154, andshunts or blocks harmonic currents, such as provided to a load, aninverter/converter 130, a drive 4820, a variable frequency drive 3840,and/or an AC drive 4830. As illustrated, the harmonic filter transformsthe current profile as a function of time from an initial profile 4995to a filtered profile 5005, such as with 5^(th) order harmonics andbeyond removed by at least 50, 75, 90, or 95%. The filter andcorresponding circuit card essentially looks at a current and provides afixed pulse width output profile. As illustrated, a contactor controller4810 is used to open/shut one or more contactors linked to the harmonicfilter 5000, as further described infra. Generally, a contactor is anelectrical device that is used for switching an electrical circuit on oroff. These contacts are, in most cases, typically open and provideoperating power to the load when the contactor coil is energized.Contactors are most commonly used for controlling electric motors. Forexample, 99+% of time, drive load turns on contactors; however,occasionally it is desirable to break contactors connection. When thisis done, the grid is still linked to the drive via the inductors.

Still referring to FIG. 48 and referring now to FIG. 49 the contactorcontroller 4810, used to connect or disconnect capacitors, is furtherdescribed. Generally, the contactor controller 4820 is a power sensorthat turns a contactor, further described infra, on or off. Forinstance, the generator 154 operates with the contactor open until apower threshold is reached, which trips the contactor to disconnect theharmonic filter 5000. The contactor functions to allow start-up orshut-down without tripping a fault circuit on the generator 154. Asillustrated in FIG. 49 , the contactor controller 4810 operates onoutput from the electrical power source 10, such as by taking/sensingpower input 4910 and generating output required to drive contactors4920, such as 5V or 15V output. For example, the 5V or 15V output isinput into a contactor drive circuit 4930, of the contactor controller4810, which reads a drive input current 4940 and using a userconfigurable variable resistor 4950 drives the contactors 4960.Contactors used in conjunction with the harmonic filter 5000 are furtherdescribed infra. An example is provided herein to further elucidate thecontactor.

Example I

In a first example, the contactor operation is further described forclarity of presentation and without loss of generality. In this example,an oil/gas industry pump is designed to operate with the contactor in aclosed (power flowing) state at higher levels of current and to open atlow current. For instance, the user configurable variable resistor 4950might be set to on at a particular load, such as a 25% load, and/or toturn off at a particular load, such as a 15% load.

Harmonic Filter

Referring now to FIG. 50 , a harmonic filter 5000 is illustrated. Asillustrated, the harmonic filter 5000 filters 3-phase power, U, V, W.Each phase of power is filtered with a coupled inductor 5010—inductor5020 pair linked together with a delta circuit, described infra. Thecoupled inductor 5010 has two or more windings on a common core andoperates as both an inductor and a transformer. The harmonic filter 5000also includes a delta-circuit 5030. An exemplary delta circuit 5030includes three hot conductors and optionally a ground. The phase loadsare connected to one another in the shape of a triangle forming a closedcircuit. As illustrated, a first coupled inductor—inductor pair 5001 isconnected to a first apex of the delta circuit 5030, such as from the Uphase; a second coupled inductor—inductor pair 5002 is connected to asecond apex of the delta circuit 5030, such as from the V phase; and athird coupled inductor—inductor pair 5003 is connected to a third apexof the delta circuit 5030, such as from the W phase. Optionalcontactors, connected to the harmonic filter 5000, are used toalternatingly connect and disconnect the delta circuit 5030, as furtherdescribed infra.

The harmonic filter 5000 takes out higher frequency harmonics. Forinstance, when processing 50 Hz signal, higher order harmonics areremoved, such as removal of 300 Hz (5^(th) harmonic), 400 Hz (7^(th)harmonic), and 500 Hz (9^(th) harmonic), which would otherwise distortthe power grid.

In one embodiment of the invention, the harmonic filter is constructedusing any of the toroids, inductor cores, core materials, and/orwindings described herein.

Cooling

Referring now to FIG. 51A, FIG. 51B, FIG. 51C, FIG. 51D, and FIG. 51E,an optionally cooling process 5100 of the harmonic filter 5000 isdescribed. As described, supra, the harmonic filter includes a coupledinductor 5010-inductor 5020 pair in-line with each phase of the 3-phasepower system. As illustrated, first various inductors in the harmonicfilter 500 are optionally staggered in vertical position relative tosecond various inductors in the harmonic filter 5000, which aids incooling as described herein. For clarity of presentation and withoutloss of generality, examples provided infra illustrate the coupledinductors 5010 of the coupled inductor—inductor pairs in a top layer andthe inductors 5020 of the coupled inductor—inductor pairs in a bottomlayer in a cooling shroud 452. However, any of the inductors in thecoupled inductor-inductor pair, such as the first coupledinductor—inductor pair 5001, described supra, are optionally on the samelevel and/or are positioned in any orientation on differing levels.

Example I

In a first example, the coupled inductors of the coupledinductor—inductor pairs are positioned in a first cooling layer and theinductors of the coupled inductor-inductor pairs are positioned in asecond cooling layer. More particularly, referring now to FIG. 51A,three coupled inductors 5010 (of coupled inductor-inductor pairs) arepositioned in a first layer within a cooling shroud 452, which is anexample of the air guide shroud 450. Still more particularly, a firstcoupled inductor 231, a second coupled inductor 232, and a third coupledinductor 233 are positioned in the first layer, where each of thecoupled inductors 231, 232, 233 are linked to individual phases of the3-phase grid system. Similarly, referring now to FIG. 51B, threeinductors 5020 (of coupled inductor—inductor pairs) are positioned in asecond layer within the cooling shroud 452. Still more particularly, afirst inductor 237, a second inductor 238, and a third inductor 239 arepositioned in the second layer, where each of the inductors 237, 238,239 are linked to individual phases of the 3-phase grid system. Asillustrated, the x-, y-positions of the first, second, and third coupledinductors 231, 232, 233 are staggered relative to x-, y-positions of thefirst, second, and third inductors 237, 238, 239, which forces airflowing between levels along the z-axis to travel back and forth alongthe x- and/or y-axes, which aids cooling.

Referring still to FIG. 51A and FIG. 51B and referring now to FIG. 51Cand FIG. 51D, the z-axis alignment of the inductors in the coupledinductor-inductor pairs, such as the first, second, and third coupledinductor—inductor pairs 5001, 5002, 5003 is further described. Asillustrated, one or more fans 5110, such as a first fan 5111, a secondfan 5112, and/or a third fan 5113 push, and/or optionally pull, airthrough the cooling shroud 452, where the cooling air takes directand/or tortuous paths between, around, and/or through the inductors. Forinstance, referring now to FIG. 51D, a first air flow path, A, travelsaround the inductors and within the cooling shroud 452; a second airflow path, B, travels around the some inductors and through otherinductors within the cooling shroud 452; and/or a third air flow path,C, travels around first inductors on a first level and around secondinductors on a second level within the cooling shroud 452.

Example II

Referring now to FIG. 51E, an exemplary representation of housing thecoupled inductors 5010 and the inductors 5020 in the coupledinductor-inductor pairs 5001, 5002, 5003, described supra, is provided.As illustrated, the coupled inductor-inductor pairs 5001, 5002, 5003 aremounted on racks 5120 or rails in a cabinet, such as a hip cabinet,further described infra, and are optionally and preferably cooled by oneor more fans placed in the hip cabinet or in a tube, as furtherdescribed infra.

Optionally and preferably, the inductors in the previous two examplesare mounted in an orientation with the air flow traveling vertically;however, the inductors in the cooling shroud 452 are optionallypositioned in any orientation.

Inductor Mounting

Referring still to FIG. 51E and referring now to FIG. 52 A and FIG. 52B,an inductor mounting system 5200 is described. Generally, the inductormounting system 5200 resembles the vertical mounting system where aclamp bar 234 passes through a central opening 310 in the inductor 230and is clamped to the base plate 210 via ties 315, albeit with lessclamping force. Here, an inductor 230 is fastened to the rack 5120 witha tiedown strap 5210, such as a first tiedown strap 5211 fastened at onepoint to the rack 5120 and, after wrapping along an outer edge, an outersurface, and through a central opening of the inductor 230, is fastenedat another point to the rack 5120. Similarly, a second tiedown strap5212 is optionally and preferably used to force the inductor 230 towardthe rack 5210, where the second tiedown strap 5212 is optionally andpreferably positioned at least 115 degrees around an axis passingthrough the central opening of the inductor 230 relative to the firsttiedown strap 5211. Generally, any number of tiedown straps 5210 areused. As illustrated in FIG. 52B, a tiedown strap, which isalternatively a bolt based fastener, is applied with a force of 10 to100 pounds of force/tension and preferably within five pounds of 30, 40,50, or 60 pounds of force. Optionally and preferably, the tiedown straps5210 are non-conductive, such as Glastic straps, a pultruded strap,and/or fiber reinforced plastic.

As mounted, optionally and preferably individual inductors 230 aremounted with one or more of the following properties:

-   -   in a duct/cooling shroud/housing;    -   with a fan forcing air through the duct/cooling shroud/housing;    -   with a fan pulling air through the duct/cooling shroud/housing;    -   attached with less force than a vertically mounted inductor,        which is preferably mounted with 200 to 800 pounds of strap        force;    -   in a stacked orientation relative to other inductors in the        duct/cooling shroud/housing;    -   rotated about a longitudinal axis passing through the        duct/cooling shroud/housing relative to other inductors; and/or    -   in a cabinet, such as in a drive cabinet, in a hip cabinet        attached to the drive cabinet, or in a separate cabinet from a        drive housing cabinet.

Harmonic Filter

Referring now to FIG. 53 , a harmonic filter 5000 and/or a highfrequency filter 144 is optionally and preferably used to process/filtercurrent passing between: (1) the inverter/converter 130 and/or a highfrequency inverter 134 and the load 152, motor 156, or a permanentmagnet motor 158 and/or (2) a drive 151, such as a variable frequencydrive 3840 and a load 152, such as a motor 156.

Harmonic Filter Contactor

Harmonic filter contactors are used to alternatingly connect the coupledinductor 5010 to the delta circuit, such as under control of thecontactor controller 4810 described supra. As described herein, placingcontactors within the delta circuit 5030 greatly reduces expense of thecontactors. Four examples are provided with contactors positioned indifferent locations, where the overall cost of the harmonic filter 5000decreases in each subsequent example.

Example I

In a first example, still referring to FIG. 50 and referring now to FIG.54 , as illustrated optional main line contactors 5040 are positionedbetween a given coupled inductor 5010-inductor 5020 pair and a givenapex of the delta circuit 5030. For instance, a first main linecontactor 5041, C_(1a), connecting the U phase, is positioned betweenthe first coupled inductor—inductor pair 5001 and the first apex of thedelta circuit; a second main line contactor 5042, C_(1b), connecting theV phase, is positioned between the second coupled inductor—inductor pair5002 and the second apex of the delta circuit; and/or a third main linecontactor 5043, C₁c, connecting the W phase, is positioned between thethird coupled inductor—inductor pair 5003 and the third apex of thedelta circuit, where any two of the first, second, and third contactors5041, 5042, 5043 function to alternatingly connect and disconnect thedelta circuit 5030 and/or the capacitors therein. A primary problem withthe main line contactors is expense. For instance, when filtering 500 Acurrent, each contactor must connect/disconnect approximately 200 A.This size contactor currently costs about $4,000, where costs ofcontactors drops exponentially with decreased amperage requirements.

Example II

In a second example, still referring to FIG. 50 and referring now toFIG. 55 , as illustrated the optional main line contactors 5040 arereplaced with delta leg contactors positioned on legs of the deltacircuit 5030 between the apexes of the delta circuit 5030. For instance,the first main line contactor 5041 is replaced with two delta legcontactors 5510, such as a first delta leg contactor 5511 on the UW leg5031 of the delta circuit 5030 and a second delta leg contactor 5512 onthe UV leg 5032 of the delta circuit 5030. Stated again, the first andsecond delta leg contactors 5511, 5512 optionally replace the first mainline contactor 5041, where the cost of the contactors operating on thelegs of the delta circuit 5030 are reduced to $500 as a result of onlyhaving to handle 100 A within each leg of the delta circuit as opposedto 200 A in the lead from the first couple inductor-inductor pair 5001to the delta circuit 5030, which as noted above had to handle 200 A.Similarly, the second main line contactor 5042 is optionally replacedwith two delta leg contactors 5510, such as a third delta leg contactor5513 on the VW leg 5033 of the delta circuit 5030 and a fourth delta legcontactor 5514 on the UV leg 5032 of the delta circuit 5030. As above,the third and fourth delta leg contactors 5513, 5514 replace the secondmain line contactor 5042 and again the price of the two smaller deltaleg contactors is far less than the main line contactor as the 200 Acurrent on the main line is split to 100 A on each delta leg of thedelta circuit 5030. In practice, only three delta leg contactors 5510are need to disconnect the delta circuit from the electrical powersource 10 or the load, such as the first, second, and third delta legcontactors 5511, 5512, 5513 or the first, third, and fourth delta legcontactors 5511, 5513, 5514. Similarly, one or two delta leg contactorsare optionally used to disconnect the W phase power, not illustrated forclarity of presentation. Again, disconnecting any one contactor on eachof the three legs of the delta circuit functions in practice todisconnect the delta circuit 5030 from the electrical power source 10 orthe load. Notably, the 100 μF capacitors in each leg of the delta filter5030 in the previous example are optionally and preferably replaced bytwo 50 μF capacitors wired in parallel in each leg of the delta filter5030 in the current example. This example illustrates that's contactorswithin legs of the delta filter 5030 are optionally used in place ofcontactors positioned between a given coupled inductor-inductor pair andthe delta filter 5030, where the given coupled inductor-inductor pairfilters a given phase of multi-phase U, V, W current.

Example III

In a third example, still referring to FIG. 50 and referring now to FIG.56 , as illustrated the optional main line contactors 5040 and/or thedelta leg contactors 5510 are optionally and preferably replaced withparallel delta leg contactors positioned on legs of the delta circuit5030 between the apexes of the delta circuit 5030. For instance, thefirst main line contactor 5041 and/or the first delta leg contactor 5511on the UW leg 5031 of the delta circuit 5030 is optionally andpreferably replaced with two parallel delta leg contactors 5610, such asa first delta leg contactor, c_(3a), on the UW leg 5031 of the deltacircuit 5030 and a second delta leg contactor, cab, on the UW leg 5031of the delta circuit 5030.

Stated again, the first and second electrically parallel delta legcontactors are optionally used to replace the first main line contactor5041, where the cost of the contactors operating on the legs of thedelta circuit 5030 are reduced to $50 as a result of only having tohandle 50 A within parallel electrical paths on the leg of the deltacircuit as opposed $4000 contactors in the lead from the first coupledinductor-inductor pair 5001 to the delta circuit 5030, which as notedabove had to handle 200 A. Similarly, the UV leg 5032 of the deltacircuit 5030 is optionally and preferably alternatinglyconnected/disconnected using two contactors wired in parallel in the UVleg 5032, the contactors labeled c_(3c) and c_(3d). Similarly, the VWleg 5033 of the delta circuit 5030 is optionally and preferablyalternatingly connected/disconnected using two contactors wired inparallel in the VW leg 5032, the contactors labeled c_(3e) and c_(3f).Again, breaking the connection of each leg with the contactors issufficient to disconnect the delta circuit 5030 from the electricalpower source 10 or load. Generally, this example illustrates that two ormore contactors wired in parallel handling less current in a given legof the delta circuit 5030 are optionally and preferably used in place oflarger and more expensive contactors between a given coupledinductor—inductor pair and the delta circuit 5030, as illustrated in thefirst example.

Notably, in the first example each leg of the delta circuit used 100 μFcapacitors, which are optionally and preferably replaced with two 50 μFcapacitors in the second example and four 25 μF capacitors in the thirdexample.

The third example is a preferred embodiment as the contactor cost perleg has reduced from $4,000 currently to $100 through use of the smallercontactors. However, in the fourth example, described infra, it isdemonstrated that still smaller contactors are optionally used.

Example IV

In a fourth example, still referring to FIGS. 50 and 56 , as illustratedthe optional main line contactors 5040, the delta leg contactors 5510,and/or the parallel delta leg contactors 5610 are optionally replacedwith a set of 2, 3, 4, or more delta contactors 5620, such as theillustrated c_(4a), c_(4b), c_(4c), and c_(4d) contactors for the UWdelta leg 5031; the illustrated c_(4e), c_(4f), c_(4g), and c_(4h)contactors for the UV delta leg 5032; and the illustrated c_(4i),c_(4j), c_(4k), and c_(4l) contactors for the VW delta leg 5033.However, gains made in reduced contactor price versus labor isnegligible at this point. Again, breaking the connection of each legwith the contactors is sufficient to disconnect the delta circuit 5030from the electrical power source 10 or load.

Notably, the contactors used are separately selectable for each leg ofthe delta filter 5030. For instance, the delta leg contactors 5510 areoptionally used on one leg of the delta filter 5030; the parallel deltaleg contactors 5610 are optionally used on another leg of the deltafilter 5030; and even a set of two delta contactors are optionally usedin parallel with one of the parallel delta leg contactors 5610.

Filter

Referring now to FIG. 57 and FIG. 58 , three electrically parallelinductors are illustrated filtering current without and with acapacitor, respectively. If made with electrolytic capacitors, thecircuits may require oil cooling and/or are not fully able to carry aload in the cold. For instance, for a 200 ampere current, a traditional100 μF capacitor cannot handle higher ripple current, such as from anoisy power grid. However, if the described circuits are made withmetallized film capacitors, these limitations are overcome, as furtherdescribed infra. Further, magnetic flux passes between all 3-phases inthe circuits illustrated in FIG. 57 and FIG. 58 .

However, in the harmonic filter 500, the 3-phases, such as in the powergrid, are magnetically isolated.

Metallized Film Capacitors

Referring now to FIG. 59A and FIG. 59B, a metallized film 5900 isillustrated. The metallized film 5900 is used to construct a metallizedfilm capacitor 5930, which is optionally used in place of any capacitordescribed herein. As illustrated, the metallized film 5900 includes ametal side 5910, such as an aluminum side, and an insulator side 5920,such as a plastic side. Optionally and preferably, the harmonic filters5000 described herein are produced with one or more metallized filmcapacitors. The metallized film capacitors are optionally and preferablynon-electrolytic. One advantage of the metallized film capacitor 5930 isan ability to operate and/or carry 100% load in the cold, such as atless than 60, 50, 40, 30, 20, 10, 0, −10, or −20° F. Another advantageof the metallized film capacitor 5930 is ability to operate withoutbeing submersed in oil, where traditional capacitors fail at coldtemperatures due to changes in the oil heat transfer properties. Stillanother advantage of the metallized film capacitor 5930 is the abilityto handle 60 Hz current, such as at greater than 50, 60, 75, 100, or 500amperes, such as in a polyphase power system.

Inductor Shape

Referring now to FIG. 60A, FIG. 60B, FIG. 60C, and FIG. 60D, optionallyand preferably any of the inductors 230 described herein are optionallyconstructed with any geometry circumferentially surrounding a centralopening. for example, the inductor core 610 optionally has a circularcross-section 610, FIG. 60A; an oblong cross-section 6020, FIG. 60B; asquare cross-section 6030, FIG. 60C; and/or a rectangular cross-section6040, FIG. 60D, such as for one or more phases of a multi-phase powersystem. Generally, the inductor 230 optionally has an aperturetherethrough, such as through a center of the inductor 230, where theinductor has rotational symmetry or lacks rotational symmetry. Forinstance, the inductor core of a circular inductor has infiniterotational symmetry, C_(∞) rotational symmetry, as the inductor core, isthe same upon rotation about an axis passing through the center aperturewithout contacting the core, such as along a z-axis passing through anannular inductor laying on its face. Similarly, an oval inductor coreand/or a rectangular core has C₂ rotational symmetry; a triangularinductor core has C₃ rotational symmetry; a square inductor core has C₄rotational symmetry; and so on, where rotational symmetry results in anobject looking the same with rotation about an axis.

Mechanically Fabricated Winding

Referring now to FIG. 61 , an inductor 230 with a mechanically assembledwinding 6205 is illustrated about an inductor core 610. Herein, anassembly using the mechanically assembled winding 6205 about theinductor core 610 is referred to as an inductor 230 and/or amechanically fabricated inductor 235.

Still referring to FIG. 61 , manufacture of the mechanically fabricatedinductor 235 is described. In a traditional toroidal inductor 230, awinding is a continuous wire, where each turn of the continuous wire ispassed through the central opening 310 during manufacture, which is atime consuming process. In stark contrast, in the mechanicallyfabricated inductor 235, a winding is not a continuous wire. Rather,each one or more turns of the mechanically assembled winding is puttogether from sections, such as sections attached to each other in afabrication step as opposed to a continuous length of wire. For clarityof presentation and without loss of generality, as illustrated, eachmechanically assembled turn, of the mechanically assembled winding 6205,is illustrated as a first part 6210, such as a C-section, that ismechanically fastened to a second part 6220, such as a rod-section.However, more generally each mechanically assembled turn, of themechanically assembled winding 6205, optionally and preferably includesgreater than 1, 2, 3, 4, 5, or more sections that are fastened together,such as via a bolt, a weld, plugs, clips, and/or formation of one ormore electrical connections. Several examples are provided to clarifythe manufacture of the mechanically fabricated inductor 235 and/or thestructure of the mechanically fabricated inductor 235.

Example I

Still referring to FIG. 61 and referring now to FIG. 62A, FIG. 62B, andFIG. 62C, the mechanically assembled winding 6205 is further described.In this example, the mechanically assembled winding 6205 includes twosets of parts: a first set of first parts 6210 and a second set ofsecond parts 6220. More particularly, in this example, the first set offirst parts 6210 includes a first C-section 6211, a second C-section6212, and a third C-section 6213 of n C-sections. Similarly, the secondset of second parts 6220 includes a first rod-section 6221, a secondrod-section 6222, and a third rod-section 6223 of n rod-sections, wheren is a positive integer of greater than 0, 1, 2, 3, 5, 10, 15, 20, 25,30, 40, or 50. As illustrated in FIG. 61 , during assembly the firstC-section 6211 is fastened to the first rod-section 6221, such as withany fastening/electrical connection technique. As illustrated in FIG.62B, each of the C-sections are twisted to allow a first coupling end6214 of the C-section to connect to a first rod-section, such as thefirst rod-section 6221, and a second coupling end 6216 of the C-sectionto connect to a second rod-section, such as the second rod-section 6222.Hence, referring again to FIG. 61 , the second C-section 6212 connectsto the first rod-section 6221 on the bottom (out of view as illustrated)and to the second rod section 6222 on the top of the inductor core 610.Similarly, the third C-section 6213 connects to the second rod-section6222 on the bottom (out of view as illustrated) and to the third rodsection 6223 on the top of the inductor core 610. This process repeatsuntil the terminal connector sections are reached, as further describedinfra. More generally, each turn of the mechanically assembled winding6205 is created from two or more parts that are fastened together toform electrical connections. Referring again to FIG. 62A and FIG. 62B,as illustrated the first rod-section 6221 optionally and preferablycontains a rod 6224 that is threaded 6226 for insertion into a tappedhole 6218 of the first coupling end 6214 and a bolt head 6225 forattaching/screwing in, through the rotationally previous C-sectionsecond coupling end 6216, the rod 6224 to the tapped hole 6218, wherethe first coupling end 6214 and the second coupling end 6216 areseparated by a relief section 6215. Referring still to FIG. 61 andreferring now to FIG. 62C, at the electrical ends of the formedmechanically assembled winding 6205, connectors 6230 are used to connectto input and output lines, such as a via a first connector 6131connecting to an input and a second connector 6132 connecting to anoutput. Notably, the input connector 6131 and the output connector 6132are optionally the same shape, which eases manufacturing the componentparts, and are simply flipped during fabrication of the mechanicallyassembled winding 6205. As illustrated, the input connector 6131optionally and preferably contains a connector section 6234 with afastener aperture and/or tapped hole 6236 therein and a windingconnector section 6233 and an aperture therethrough, such as for passageof the bolt section/rod 6224 therethrough.

Example II

Still referring to FIG. 61 , optionally and preferably each turn of themechanically assembled winding 6205 is fabricated from at least a firstpart 6210 and a second part 6220 of n parts where the first and secondparts 6210, 6220 are joined to form an electrical connection within thewinding, such as via cold welding, joining, welding, electricallyjoining, and/or a mechanical connection, such as bolting together. Theelectrical connection is optionally one or more of: a light dutyconnector for up to 250 volts; a medium duty connector for up to 1000volts; and a heavy duty connector for up to 300,000 volts. Optionallyand preferably, a work-station and/or a multiple part holding guide isused to weld multiple connections at the same time, such as one or moreelectrical connection per turn.

Example III

Still referring to FIG. 61 , the mechanically assembled winding 6205 isconstructed of aluminum and/or at least 80, 90, 95, or 99% aluminum, analuminum alloy, or copper. The winding wire is optionally painted orcoated with any coating, such as a rubber coating, a plastic coating, oran anodization.

The mechanically assembled winding 6205 is optionally and preferablyused with any system described herein, such as in the inductor in a tubesystem 6300 described infra.

Inductors in a Tube

Referring now to FIG. 63A, FIG. 63B, and FIG. 63C, an inductor in a tube6300 system is described. Referring now to FIG. 63A, an elongated tube6310 forms a housing. Two or more, and preferably three inductors aremounted on a multi-inductor baseplate 6320, such as the baseplate 210.As illustrated in FIG. 63B, a first inductor 237, a second inductor 238,and a third inductor 239 are vertically mounted to the multi-inductorbaseplate 6329, such as with the vertical mounting and/or strap tiesystems described supra. For example, the first inductor 237, or anyinductor, is fastened to the multi-inductor baseplate 6320 prior toinsertion into the elongated tube 6310, such as with a vertical mountingtiedown strap 6323 and/or a bolt and clamp mechanism, such as the clampbar 234/ties 315 combination described supra. Optional spacers 6340 areused to maintain a distance between the inductors. Optionally andpreferably, the elongated tube 6310 is longitudinally divided/separatedby an elongated gap 6316 and/or the multi-inductor baseplate 6320running along the length of the elongated tube 6310 into a first section6312, such as a first half, and a second section 6314, such as a secondhalf. The elongated separations allows mounting of the inductors on themulti-inductor baseplate 6320 followed by placing the parts of theelongated tube 6310 around the inductor/baseplate assembly.Particularly, bringing the elongated tube 6310 together along the y-and/or the z-axes, where the length of the tube is the x-axis, allowsfor the electrical connections to a three phase power supply to beaccessible, such as illustrated in FIG. 63C. Particularly, asillustrated a first pair of contactors 6331 connected to the firstinductor 237; a second pair of contactors 6332 connected to the secondinductor 238; and a third pair of contactors 6333 connected to the firstinductor 239, which would otherwise block insertion of the inductorsinto the elongated tube 6310 are: (1) insertable as a result of bringingthe elongated tube 6310 together laterally and/or (2) accessible forconnection to the multi-phase grid. Optionally, the multi-inductorbaseplate 6320 is positioned within the elongated tube 6310 or is usedas a separator between the first section 6312 and the second section6314. Optionally, one or more straps 6350 or connectors are used tofasten the first section 6312 to the second section 6314, such as afterinsertion of the first inductor 237, the second inductor 238, the thirdinductor 239, and/or the multi-inductor baseplate 6320. Optionally andpreferably, an element of the cooling system 240, such as a fan 242 isinserted into the elongated tube 6310, such as with or without mountingto the multi-inductor baseplate. The fan 242 is optionally attached toan end of the elongated tube 6310, such as after bringing the tubesections together to form the tube. More generally, the elongated tubeis optionally bent or formed in any elongated shape, such as greaterthan 80% of a circle. Further, the elongated gap 6316 is optionally anopening that allow insertion of the multi-inductor baseplate 6320 and/orone or more inductors mounted on the baseplate. In this case, theapertures are optionally through a side of the elongated tube 6310 otherthan where the elongated gap is present. Further, the elongated tube isoptionally of any cross-sectional shape, such as oblong, square, orrectangular.

Example I

In a first example, still referring to FIG. 63A, FIG. 63B, and FIG. 63C,ten inch diameter inductors are placed in a twelve inch diameterelongated tube and a two inch slot is cut in the tube for insertion ofthe multi-inductor baseplate 6320. Optionally and preferably, a gapbetween an outer perimeter of the inductors and the elongated tube ofless than 4, 3, 2, 1, or 0.5 inches facilitates cooling airflow from thefan past the inductors.

Example II

In a second example, one or more elements of the harmonic filter 5000and/or the sine wave filter 3850 are positioned in the elongated tube6310.

Hip Box

Referring now to FIG. 64A and FIG. 64B, a hip box system 6400 isdescribed. Generally, a drive cabinet 6410 holds a drive 157, such as avariable frequency drive 3840. Traditionally, the filter system wasmounted in the drive cabinet 6410, which leads to complications in termsof weight, space, and particularly cooling. The inventors have added ahip box 6420 to the drive cabinet 6410. Optionally and preferably, thehip box 6420 is mounted to a side of the drive cabinet 6410, such as atan accessible height of 3 to 7 feet off of the floor. Any of the filtersystems described herein are optionally and preferably mounted in thehip box 6420.

Example I

In a first example, the hip box 6420 houses the inductor in a tube 6300system, described supra. In this embodiment, the first, second, andthird inductors 237, 238, 239 are mounted vertically with the fan 242pushing air through the inductors. Optionally, the fan 242 pushes airout of a top of the hip box. However, optionally and preferably, airexits are out to the drive cabinet 6410 and/or out an access panel 6422access door and/or access panel vent 6426, where less than 20, 10, 5, 2,or 1 percent of the air flow from the fan exits into an volume 6421directly above the hip box 6420. As illustrated, electrical connectionlines 6330, such as to the first, second, and third pair of contactors6331, 6332, 6333 connected to the first, second, and third inductors237, 238, 239 are accessible through the access panel 6422/access door,which is optionally about five±one or two feet off of the ground. Asillustrated, the filter system is accessible without accessing the drivecabinet 6410 and a first cooling system of the filter system isoptionally separate from a second cooling system of the drive cabinet.

Optionally, any element of the inductor, such as a winding element isprinted using three-dimensional metal printing technology, such as in anadditive manufacturing process.

Optionally, any element of the inductor is constructed with a carbonnanotube.

Herein, a set of fixed numbers, such as 1, 2, 3, 4, 5, 10, or 20optionally means at least any number in the set of fixed number and/orless than any number in the set of fixed numbers.

In still yet another embodiment, the invention comprises and combinationand/or permutation of any of the elements described herein.

The particular implementations shown and described are illustrative ofthe invention and its best mode and are not intended to otherwise limitthe scope of the present invention in any way. Indeed, for the sake ofbrevity, conventional manufacturing, connection, preparation, and otherfunctional aspects of the system may not be described in detail. Whilesingle PWM frequency, single voltage, single power modules, in differingorientations and configurations have been discussed, adaptations andmultiple frequencies, voltages, and modules may be implemented inaccordance with various aspects of the present invention. Furthermore,the connecting lines shown in the various figures are intended torepresent exemplary functional relationships and/or physical couplingsbetween the various elements. Many alternative or additional functionalrelationships or physical connections may be present in a practicalsystem.

In the foregoing description, the invention has been described withreference to specific exemplary embodiments; however, it will beappreciated that various modifications and changes may be made withoutdeparting from the scope of the present invention as set forth herein.The description and figures are to be regarded in an illustrativemanner, rather than a restrictive one and all such modifications areintended to be included within the scope of the present invention.Accordingly, the scope of the invention should be determined by thegeneric embodiments described herein and their legal equivalents ratherthan by merely the specific examples described above. For example, thesteps recited in any method or process embodiment may be executed in anyorder and are not limited to the explicit order presented in thespecific examples. Additionally, the components and/or elements recitedin any apparatus embodiment may be assembled or otherwise operationallyconfigured in a variety of permutations to produce substantially thesame result as the present invention and are accordingly not limited tothe specific configuration recited in the specific examples.

Benefits, other advantages and solutions to problems have been describedabove with regard to particular embodiments; however, any benefit,advantage, solution to problems or any element that may cause anyparticular benefit, advantage or solution to occur or to become morepronounced are not to be construed as critical, required or essentialfeatures or components.

As used herein, the terms “comprises”, “comprising”, or any variationthereof, are intended to reference a non-exclusive inclusion, such thata process, method, article, composition or apparatus that comprises alist of elements does not include only those elements recited, but mayalso include other elements not expressly listed or inherent to suchprocess, method, article, composition or apparatus. Other combinationsand/or modifications of the above-described structures, arrangements,applications, proportions, elements, materials or components used in thepractice of the present invention, in addition to those not specificallyrecited, may be varied or otherwise particularly adapted to specificenvironments, manufacturing specifications, design parameters or otheroperating requirements without departing from the general principles ofthe same.

Although the invention has been described herein with reference tocertain preferred embodiments, one skilled in the art will readilyappreciate that other applications may be substituted for those setforth herein without departing from the spirit and scope of the presentinvention. Accordingly, the invention should only be limited by theClaims included below.

The invention claimed is:
 1. An apparatus, comprising: a harmonic filtercomprising: a delta circuit comprising: a first leg connecting to asecond leg and a third leg, first circuitry on said first leg matchingsecond circuitry on said second leg, said first circuitry comprising atleast two contactors electrically wired in parallel, said harmonicfilter magnetically isolating phases of three-phase power.
 2. Theapparatus of claim 1, said first circuitry comprising: at least fourcontactors electrically wired in parallel.
 3. The apparatus of claim 1,said first circuitry further comprising: at least two capacitorselectrically wired in parallel.
 4. The apparatus of claim 3, said firstcircuitry comprising: at least four capacitors electrically wired inparallel.
 5. The apparatus of claim 4, a first capacitor of said atleast four capacitors further comprising: a rolled metallized filmconstruction.
 6. The apparatus of claim 1, said delta circuit furthercomprising: a first inductor—coupled inductor pair connected to a firstapex of said delta circuit, said first inductor of said firstinductor—coupled inductor pair comprising an aperture therethrough,non-infinite rotational symmetry, and at least one of: no rotationalsymmetry; C₂ rotational symmetry; C₃ rotational symmetry; and C₄rotational symmetry; a second inductor—coupled inductor pair connectedto a second apex of said delta circuit; and a third inductor—coupledinductor pair connected to a third apex of said delta circuit.
 7. Theapparatus of claim 1, further comprising: second circuitry on said thirdleg not matching said first circuitry.
 8. The apparatus of claim 1,further comprising: a first electrical contactor and a second electricalcontactor positioned within at least two of: said first leg, said secondleg; and said third leg.
 9. The apparatus of claim 1, said delta circuitfurther comprising: a first inductor coupled to a first apex of saiddelta circuit, said first inductor comprising: a fabricated windingcomprising a plurality of turns, at least a first turn of said pluralityof turns comprising: a first sub-section and a second sub-sectionelectrically connected to said first sub-section with a first electricalconnection; a second inductor coupled to a second apex of said deltacircuit; and a third inductor coupled to a third apex of said deltacircuit.
 10. The apparatus of claim 1, said harmonic filter furthercomprising: at least one inductor electrically coupled to said deltacircuit, said inductor comprising a pressed powder core, said corecomprising an aperture therethrough.
 11. The apparatus of claim 1, saidharmonic filter further comprising: at least one inductor electricallycoupled to said delta circuit, said inductor comprising an inductor coreand an inductor winding, said inductor winding comprising: a firstwinding wire, comprising: a width extending away from said inductorcore; an inductor core contact side comprising a height; and awidth-to-height ratio of at least three.
 12. A method for processingthree-phase power, comprising the step of: filtering the three-phasepower with a harmonic filter comprising: a delta circuit comprising: afirst inductor—coupled inductor pair linked to a first apex of saiddelta circuit; a second inductor—coupled inductor pair linked to asecond apex of said delta circuit; a third inductor—coupled inductorpair linked to a third apex of said delta circuit; a first legconnecting to a second leg and a third leg; and first circuitry on saidfirst leg matching second circuitry on said second leg, said firstcircuitry comprising at least two contactors electrically wired inparallel.
 13. The method of claim 12, said harmonic filter furthercomprising the steps of: magnetically isolating a first phase from asecond phase and a third phase of the three phase electrical power withsaid harmonic filter; and magnetically isolating the second phase fromthe third phase of the three phase electrical power with said harmonicfilter.
 14. The method of claim 13, further comprising the step of:wiring said first circuitry with a first capacitor and a secondcapacitor electrically coupled in parallel.
 15. The method of claim 14,further comprising the step of: alternatingly connecting anddisconnecting said delta circuit from the three phase power by openingand closing a first electrical contactor and a second electricalcontactor positioned within at least two of: said first leg, said secondleg; and said third leg.
 16. The method of claim 14, further comprisingthe step of: filtering noise in a phase of the three-phase power with afirst capacitor and a second capacitor wired in parallel within saidfirst leg of said delta circuit.
 17. The method of claim 14, said stepof further comprising the step of: passing current of the three-phasepower along a winding about said first inductor of said firstinductor—coupled inductor pair, said winding comprising at least tenelectrical connections formed between winding sections during a windingstep of said first inductor.
 18. The method of claim 12, furthercomprising the steps of: mounting inductors of said harmonic filter on afirst rack and a second rack in a cabinet, wherein first apertures of afirst three inductors, of said harmonic filter, form a first triangle onsaid first rack; wherein second apertures of a second three inductors,of said harmonic filter, form a second triangle on said second rack,first apexes of said first triangle rotated by at least twenty degreesrelative to second apexes of said second triangle; and flowing air,driven by a fan, through said cabinet.